Lumin U1 Mini Digital Transport + Sbooster Power Suppy

tmallin

WBF Technical Expert
May 19, 2010
355
26
28
66
Chicagoland
#1
Lumin on My Radar

The Lumin products started appearing on my personal audio radar following the problems I encountered with my Auralic Aries G2 (as described in this post in the Auralic's thread).

Now, most high-end streamers are not known for ease of use or reliable functioning. Those who use general purpose computers for audio streaming have no idea how good they have it in terms of reliable, non-flaky functionality. I have found that out myself with my new headphone listening system built around my Dell all-in-one desktop computer, discussed here. I'm sure the sonics of the streamer of such a system can be bettered, but in terms of rock-solid reliability, using a "real computer" to tune to and stream directly from music streaming websites—much less connecting to local music files—holds no surprises or glitches to annoy you.

I did note, however, how much praise the Lumin units and the Lumin control app garnered both for sonics and for reliable, non-glitchy operation, as well as the supposedly top-notch GUI. Lumin also seems to be one of the most responsive companies to fixing any glitches users discover, releasing periodic fixes as well as software/firmware enhancements. These are automatically installed as released.

As before with my choice of the Auralic Aries G2, I wanted to concentrate on a unit without a built-in DAC for two reasons. First, I think my Benchmark DAC3 HGC is very natural sounding and don't want to give that up.

Second, I want to be able to use an equalizer in the digital domain to do room correction for my Harbeth M40.2 speakers. Unless the streamer incorporates digital parametric equalization (as the Aries G2 now does), that means I couldn't really use a separate digital equalizer and still use the DAC built into a streamer. While every Lumin streamer has a digital output (even though they also have onboard DACs), as far as I know, no streamer allows output of a digital signal into a digital EQ, with the output of the digital EQ then being allowed back into that streamer's DAC. There are no "pre out/power in" jacks in digital equipment as there were in some old analog integrated amps and receivers. Such two-way traffic might work via a USB hub, but, without testing it, I'm not sure.

This meant either the Lumin U1 at $6,000 or the U1 mini at $2,000. I chose the stripped-down U1 mini because of (1) the huge cost difference despite similar functionality and active parts (2) knowing that the sonics of the U1 Mini could be further improved by addition of an external linear power supply to replace the Mini's internal switch mode power supply, thus mimicking the U1 arrangement, (3) not needing the highest DSD and PCM speeds offered by the U1, and (4) figuring that the power line and anti-vibration treatments I would be using with the Mini might further close any performance gap related to the difference in chassis construction between the solid-aluminum block U1 and the assembled aluminum pieces of the U1 Mini.

Besides, if down the road I decide I really want the top Lumin streamer, I probably would not go with the U1. I'd just skip the U1 and go up to the X1 and not use the DAC in that unit. The X1's DAC would still be available if a means of applying digital EQ with that unit is feasible, such as via Roon or via firmware changes to the Lumin which might eventually add digital EQ functions to the firmware, as was the case with the Auralic Aries G2.

Enter the Lumin U1 Mini + Sbooster Power Supply

Upscale Audio in California is not only a Lumin U1 Mini dealer, but also the USA distributor for the European Sbooster external linear power supply and Lumin Connection Kit for the Sbooster which I intended to use with the U1 mini to replace its internal switch-mode power supply. I decided to order the Lumin from Upscale Audio in California, plus the Sbooster power supply and Lumin installation kit. Upscale had a black open box unit which I got for $1,800. It was pristine, as far as I could tell, both the unit and the packaging.

Sbooster Installation

I immediately installed the Sbooster kit because I wanted to make sure that was doable at my skill level. Thus, I really can't compare the sound with and without the Sbooster.

I encountered no real problems with installing the Sbooster kit; the installation directions for the kit are accurate and clear enough. I would recommend that you have a regular Torx T-10 screwdriver handy, though. The mini-handled version which comes with the kit fits the Torx screws on the U1 Mini chassis fine, but is only marginal in its ability to safely apply enough torque to remove some of those screws. The larger diameter handle of a regular T-10 driver makes the job so much easier.

However, contrary to one online description of the kit, most buyers of the Sbooster and Lumin Connection Kit will have to cut one wire. The installation directions which come with the kit call for that one wire to be cut. It's a short red wire near the back of the chassis which runs between the power switch to the IEC power inlet. The connections of that wire to the switch and inlet are soldered and then the soldered connections were covered with heat-shrink tubing. The wire is cut to allow the IEC power inlet to be removed from the chassis by pulling it out from outside the back panel of the chassis. I'm sure a competent electronics technician could remove the heat-shrink tubing and then unsolder the connection at the IEC inlet to allow the IEC inlet to be removed from the chassis and allow installation of the Lumin connection kit in the hole left by the removed IEC inlet, but performing that operation is not comfortably within my skill set. Not cutting this wire could theoretically allow the Lumin Mini internal power supply to be re-installed without obvious rewiring.

Thus, since most installers of the Lumin Connection kit will have to cut that wire, I consider this modification irreversible for most owners once it's done. I also would not count on Lumin honoring the warranty on a unit which obviously has had its internal wiring tampered with. Your retail dealer for the Lumin and/or the Sbooster would be your best recourse for warranty repair.

Once the Sbooster Connection Kit is installed, the power switch on the back of the Lumin U1 Mini is non-functional. You now turn the U1 Mini on and off with the power switch on the back of the Sbooster unit. Note that Lumin recommends that the U1 Mini remain constantly powered up anyway, so you shouldn't need to operate that Sbooster power switch very often.

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tmallin

WBF Technical Expert
May 19, 2010
355
26
28
66
Chicagoland
#2
Set Up

I placed the U1 Mini and Sbooster side by side on the top shelf of my Salamander Archetype equipment rack in the place formerly occupied by the Auralic Aries G2. As per my new usual, I treated all the non-soldered electrical connections of the components and connecting cables with the JENA Electrical Contact Enhancement Fluid recommended by P.I. Audio.

As with the Auralic Aries G2, I'm using the 1.5-meter Discrete USB cable, jointly developed by P.I. Audio and Triode Wire Labs, to connect the U1 Mini to my DSPeaker Anti-Mode X4 equalizer.

I did not try the U1 Mini with its stock power cord. Once I replaced the internal switch mode power supply of the Mini, no AC power cord is used with the Mini chassis; only a DC cable runs between it and the Sbooster.

Neither did I try the Sbooster with its stock power cord. Instead, from the beginning I used the Triode Wire Labs Digital American power cord I'd been using lately with the Auralic Aries G2. That power cord, like all the others in the system, is plugged into one of two P.I. Audio UberBUSSes. Each UberBUSS, in turn is plugged into a dedicated 20-amp circuit where the outlets are the same hand-customized Pass & Seymour 5362A receptacles P.I. Audio used in my UberBUSSes.

Since both the U1 Mini and Sbooster are very light-weight components (neither weighs more than about five pounds), I took advantage of the new Low Density (LD) Equipment Vibration Protectors (EVPs) from A/V RoomService and initially placed an LD EVP under each of the four feet of each unit. My general practice is to place the EVPs directly in contact with the underside of the component chassis at the chassis corners, but I was unable to remove the feet from the Mini and while the rubber feet of the Sbooster are removable, the screws holding the feet stick down from inside the chassis and removing them would require major disassembly of the Sbooster. I thus initially decided to place the LD EVPs under the component feet.

However, this did not work well, the resulting sound subjectively seeming bass thin/light and treble heavy when I compared the file version of tracks played via the USB stick inserted into the Lumin with the CDs from which the uncompressed WAV files were derived played by my Oppo UDP-205. Now, when such files are compared to the CD sound with both the files and CD played back through the Oppo, they are indistinguishable to me on my system. Thus, as in prior experiments, using the EVPs underneath a component's existing feet leads to strange interactive mechanical resonances which affect the subjective tonal balance of even digital equipment.

With further experiments, I found the most satisfactory arrangement of the LD EVP feet under the Lumin chassis, one which restored the sonic equality of the USB files played from the Lumin and the CD track played from the Oppo, to be as follows: Place one LD EVP near the center front edge (just behind but not touching the lip of the front panel). one at the back center edge of the underchassis, one near the left edge midway between where the two Lumin feet are mounted (just inside the lip created by the cover), and one near the right edge midway between where the two Lumin feet are mounted (just inside the lip created by the cover).

For the Sbooster, the sonically most satisfactory arrangement proved to be moving the LD EVPs immediately inboard but not touching the four Sbooster feet, with the edges of the EVPs even with the edge of the Sbooster underchassis.

For lightweight components, I'd generally recommend using the rubber version of the EVPs since this version will keep lightweight items in place on the shelf even when you connect and disconnect cables and operate controls. I thus used the rubber version of the LD EVP for the U1 Mini and Sbooster, neither of which weighs more than about five pounds.

In addition to the LD EVPs, I'm also trying out some new Cable Vibration Protectors (CVPs) from A-V Room Service with the Lumin U1 Mini + Sbooster installation. These CVPs are advertised as affording both mechanical vibration isolation and "static electrical coupling" for cables. As you can see in the pictures, they look like squares of fiberglass insulation, but from the feel of them I'm sure they are made of some other material. Using these keep cables from touching surfaces, such as floors and, as I have them deployed here, other cables and edges of wood shelving. The CVPs can be wrapped around the cables with supplied velcro strips, but I am not presently using the velcro.

Since the top plate of the U1 Mini seems to ring a bit, as with the Auralic Aries G2, I placed the same thick Music Direct catalog atop it to damp that chassic cover ringing. I found it most helpful to position the catalog so that it almost touches the front panel. This positions its weight more evenly over the four LD EVPs and note also that the back inch or two of the chassis top is just a lip and does not really cover the inside of the chassis or its components, just the back panel connections.

The Sbooster chassis seems quite "dead" all by itself. Still, I did try comparative listening experiments by adding a suitably sized thick paperback book atop the Sbooster so as to damp as much as possible of the chassis top. The long dimension of the book is critical since the front and back edges of the Sbooster are raised a bit above the main chassis. If the book is too short, it won't damp most of the chassis top; if it's too long it will sit atop one or both of the front and back lips, again not damping most of the top plate. The results of this experiment showed the sound to be a bit enhanced by addition of the book's weight atop the Sbooster chassis. The sound was a bit more focused in all dimensions without causing any decrease in the size of the presentation.

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tmallin

WBF Technical Expert
May 19, 2010
355
26
28
66
Chicagoland
#3
The only hitches I had in my set up of the Lumin U1 mini involved the stability of the internet radio function, which I use a lot. Using the Lumin app on my iPhone X, I had problems with many stations losing connectivity after a few minutes--including my favorite classical station, WFMT from Chicago. Other stations were fine for hours. I was always able to instantly restore the sound of any problematic station by just selecting the same station again, but I wasn't about to settle for that. This was never a problem with internet radio streaming via the Auralic Aries G2, by the way.

Experimenting, I determined that when the unit is controlled by the Lumin app residing on an old iPad I had, the internet radio was totally stable on the problematic stations. I thus decided to buy a new iPad 6th edition (9.5" screen, not the Pro or Air models) which Best Buy had on sale for $250 (WiFi only, 32 gig). You rarely see current Apple stuff on sale and this was a substantial discount from the regular $329 price. Since this new iPad is totally dedicated to controlling the Lumin, I took off all unneeded apps and installed only the apps I use for streaming. Plus, via the Settings menu, I turned off all unneeded functions (a boatload—it takes a while to search all the menus and submenus to find all the settings which can be adjusted to turn off unneeded functionality) just to keep the iPad processor as "unbusy" as possible. This iPad controller works wonderfully and seems totally stable with all internet radio and other functions so far.

Part of the now-rock-solid stability is also related to installing the $25 TP-Link Wireless N300 2T2R Access Point which Upscale Audio recommended as a means of providing the Lumin U1 Mini with a wired ethernet internet connection. Unlike the Auralic Aries G2, none of the Lumin streamers are inherently WiFi capable.

Since I don't have an ethernet connection available in my audio room, the TP Link device is set up in Client Mode to feed the Lumin. In Client Mode the TP-Link doesn't broadcast or extend your router's Wi-Fi. It just receives your router's Wi-Fi signal and provides a wired ethernet connection to devices which are not inherently Wi-Fi capable from its RJ-45 ethernet port on the back of the TP-Link device. After determining a strong Wi-Fi reception spot near my equipment rack, I placed the TP-Link in that spot on the floor next to my equipment rack. From there the TP-Link grabs the WiFi signal from my Xfinity Advanced Gateway and feeds it via a few feet of CAT7 cable to the ethernet connection of the Lumin. The set up of the TP Link is super simple once you see it demonstrated on video (ignore the overly complex user manual!) and takes at most five minutes.

I had been using an old Apple Airport Express in Client Mode mounted in the same spot to provide internet to the Lumin. That was okay once I had the new iPad, but very occasionally there were momentary hiccups. The TP-Link seems to provide an absolutely stable signal to the Lumin; there have been no dropouts at all.

While some may object that this TP Link device only works on the 2.4 GHz WiFi band and not the speedier 5 GHz band, Upscale claims they tested this device in their store and it seems totally comfortable streaming even DSD 512 material to a Lumin device. Remember that the Lumin is the only device served by the TP-Link set up in Client Mode. And since I'm dealing only with at most 192/24 PCM, I'm sure the TP Link's bandwidth is adequate. If it were not, I would not have the rock-solid stability of connection I now have.

The TP Link uses a 9-volt wall wart switch mode power transformer. The cable on that transformer is not quite long enough to reach my UberBUSS from the good WiFi reception spot where I placed the TP Link without running the power cord in a visible manner. I thus purchased and installed an aftermarket 9-volt iPower power supply from iFi, one having both a much longer cord and claiming to be much quieter in terms of electrical noise.

I have a two-meter Apple charging cord and 12-volt Apple charger that can reach from a wall outlet to my listening seat so that I can always keep the iPad at full charge despite having the screen on all the time and often continuously streaming music via AirPlay to the Lumin. When not in hand-held use, the dedicated iPad sits on a little stand on the floor near the wall just beyond the carpeted area of the room, just a few feet from and in line of sight of the TP-Link and Lumin. This keeps the charging cord from being a trip hazard when entering the room and keeps the Wi-Fi connection from the iPad to the TP-Link and Lumin strong. Sometimes I leave the charging cord connected while listening and handling the iPad; other times I disconnect it first. I hear no appreciable sonic difference between these two conditions even when streaming music from the iPad via AirPlay to the Lumin. Running the Speed Test by Ookla on the iPad, the iPad tests at about 500 mbps download, 40 mbps upload from either its stand position or from the listening chair via my Comcast Gigabit internet service. Thus, the iPad is not a bottleneck in the streaming path in any way since its 5 GHz connection download speed exceeds the 2.4 GHz 300 mbps capability of the TP-Link.


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tmallin

WBF Technical Expert
May 19, 2010
355
26
28
66
Chicagoland
#4
The Lumin App

In short, the Lumin App is a joy to work with. This is despite the issues noted in the next section. Now, by "the Lumin App," I'm lumping in not only the app itself, but also the software and firmware behind it, everything necessary to provide the interface between the user and the streamed files and programs.

With the Lumin App, I don't have to worry if my next command will shut down the interface, grind away forever, do something totally unexpected, give me an error message, or even just be slow (as in several seconds or more) to be recognized and acted upon. There are no hesitations, no glitches. Everything works as you would expect, quickly and in a way which produces confidence, ease, and enjoyment.

In this way it is far, far superior to my experience of Lightning DS operating the Auralic Aries G2. While the interfaces are similarly good looking and informative, there the similarity ends. Functionally, the Lumin and Auralic aren't even playing in the same league.

The Lumin App, by drawing all my streaming sources (local files, internet streaming services like Spotify, Tidal, & Qobuz, plus millions of internet radio stations and other sites like YouTube) together so seamlessly, makes even direct access to streams via my desktop computer seem rather primitive. Not that the Lumin is any more reliable than computer surfing, but the Lumin is easier since all the sources are there for the choosing in one coherent interface that a computer desktop or even drop-down lists of favorites within a browser cannot match.

With the Lumin App there have been no problems at all accessing all my music files which I have on a 1-terabyte USB stick plugged into the back of the Lumin. That sort of connection gave the G2 fits. Keeping the USB stick plugged in also does not seem to degrade the sonic quality of other Lumin streaming programs or impair the functionality of the app in any way.

Thus, I no longer need the Oppo UDP-205 to play back my files from the USB stick or any future CDs I transfer to files on that stick. All I really need the Oppo for is to play test CDs, such as for test tones used to measure frequency response via my OmniMic V2 Acoustic Measurement System. I could copy the test CD to files as well, but I think it's more convenient to use the Oppo remote to control test tone playback than trying to do that from files.

But since I don't plan to use the Oppo much anymore, I got rid of the special Kanex Pro Audio De-Embedder HDMI connection from the Oppo and am just using the Oppo's coax digital output now. Less wires, boxes, and power cables--neat and tidy. All I needed the Kanex for was playback of high-res discs and files from the Oppo and now that those are on the USB stick and that stick works fine plugged into one of the Lumin's USB ports, the Kanex is not needed.

Lumin App Issues

Playing Entire Album

Okay, nothing is perfect. Despite many reports of the Lumin App being so intuitive, I had a hard time figuring out how to do something which was very simple with Auralic's Lightning DS: playing an entire album. I think this is because Lightning DS is primarily organized to play tracks and albums, whereas the Lumin App primarily assumes the user will be constructing and playing playlists. Having only recently migrated from hard-copy CD media to files, I'm used to grouping songs by albums. I've never used playlist-oriented software before, so I did not find this aspect of the Lumin App at all intuitive.

But once I studied Lumin's "How to Use the Lumin App" instructions awhile, I figured it out. Once I saw the method, following the instructions was easy and within minutes selecting all the tracks in an album for sequential playback via a playlist became second nature. Issue totally resolved.

Incorrect Artwork Displayed and Limited Sorting Available

I also noticed early on that my local files on the USB stick don't display the proper artwork in some instances until I drill down to the track level from the album level. The album titles are always correct, but artwork displayed at the album level seems to be that of the alphabetically first album by that artist. I don't believe this is really a fault of the Lumin. It probably relates to either the formatting of my USB stick, or the fact that I'm not accessing the files via a UPnP server.

My lack of using a server is certainly what is preventing the Lumin app from displaying some of the available sorting features as to my local files, such as sorting by song title, artist, composer, genre, and year. I'm used to sorting by album/folder anyway, and that is what is displayed. Certain comments by Peter Lie, Lumin Firmware Lead, on the Lumin forum, clearly indicate that this is caused by the fact that I'm not accessing the files through a server at all, just via the USB stick inserted into one of the Lumin's USB port. For files located on the internet, such as those sourced from Tidal or Qobuz, all the expected sorting features and information are present. If I eventually install Roon and my music files on a home network computer and use the Lumin as a Roon endpoint to access my music files, I'm pretty sure this issue will go away.

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tmallin

WBF Technical Expert
May 19, 2010
355
26
28
66
Chicagoland
#5
Tune-In Radio

I'm not thrilled with Lumin's choice of Tune-In Radio as the native internet radio aggregation service supported by the App. Tune-In Radio does not have access to nearly the number or international diversity of stations as the V-Tuner app built into the Auralic Aries G2. In addition, Tune-In Radio as currently implemented in the Lumin App does not allow the user to save as a favorite any custom radio stream. You can tune to such a stream through Tune-In, but you cannot save that URL as a favorite the way you can with the Auralic's V-Tuner. In addition, even with my Premium Tune-In subscription, some streams Tune-In has built in are not the highest quality available for that station. Since you cannot save as favorites the highest quality streams you can find by URL, there is no way to build into the Tune-In app those higher quality streams the way you can with Auralic's V-Tuner.

In addition, Tune-In Radio, at least as implemented in the Lumin App, does not display what most radio stations are playing at the moment (artist, song), much less the quality of the stream (bit depth and sample rate), all of which are helpful bits of information to have, especially the song and artist. I'm quite surprised by this since via Auralic's implementation of V-Tuner, most stations do display all that information. For me, this is by far the most serious problem I've found with the Lumin App.

There is a viable partial workaround for these Tune-In Radio problems, however. Like the Auralic Aries G2, the Lumin streamers are AirPlay compatible. But unlike the Auralic, neither enabling the AirPlay function nor plugging a USB stick into one of its USB ports to access local music files, seems to in any way impair the operation of the Lumin App. You can keep the AirPlay function (which Lumin confusingly calls "Lumin Streaming") active all the time.

With AirPlay active all the time, it's simple just to use the iPad to find and favorite (either within the Safari browser or as an icon on the iPad desktop) streams missing from Tune-In Radio, such as YouTube, Jazz Radio, Sirius/XM, and the Internet Concert Archive, to name just a few.

In addition, I do the same for the V-Tuner station list, giving me easy access to many stations missing from Tune-In as well as some higher quality streams for stations included in both services. I also have made favorites of the best streams of some of my most listened-to stations, such as Chicago's WFMT, Boston's WCRB, New York's WQXR, Minneapolis' Jazz88.FM, Rochester's WXXI, as well as various SomaFM streams.

This workaround only provides artist and track information when streaming from individual station Websites, however, and usually doesn't provide sampling rate quality information at all. Neither Tune-In Radio's own website nor the V-Tuner station list displays artist, track, or stream quality information.

For most stations, the only way to get "what's playing right now" information via the Tune-In Radio app is to use the Tune-in app, click on the "More" drop-down link once you are streaming the station from the app, then click on the station website icon. That process will open a new window on the iPad which is the station's home page and that home page, or a link accessible from it, will frequently show the "now playing" information. That's cumbersome at best.

This lack of attention to internet radio streaming is perhaps understandable. My quibbles about Tune-In Radio probably are not very important to most other users of Lumin streamers. I realize that most users of high-end streamers are much less concerned with limited quality streams like internet radio than I am. They want their streamers to natively handle Tidal and Qobuz, be a Roon endpoint, be fully compatible with other high-end music server software, and be able to handle local files including way-upsampled DSD files. The Lumin is all that. Auralic's use of V-Tuner and the information that company's Lightning DS app provides for internet radio stations is indeed unusual, but that was one of the reasons I found the Aries G2 so attractive since internet radio is a big interest of mine.

Lack of Parametric Digital EQ

This is not so much an issue as a wish list item. It would be wonderful if the Lumin App contained parametric digital equalization functions the way Auralic's Lightning DS now does. Since I now can use the Lumin for all my music listening, if the Lumin had parametric digital EQ, I might be able to dispense with the separate box DSPeaker Anti-Mode X4 downstream equalizer. Perhaps such equalization will be added in a coming firmware upgrade. Here's hoping.

If THAT happened, I might be persuaded to upgrade to the X1 and run it's balanced analog output directly into my Benchmark HPA4 for volume control and headphone amp capability, dispensing with both the DSPeaker X4 and Benchmark DAC3 HGC. Or, even a wilder idea, I could drive my Benchmark AHB2 amps directly from a Lumin X1, using the Lumin's digital volume control, eliminating even the Benchmark HPA4 since I don't really need headphone sound in my audio room now that I have a well-tuned desktop electrostatic headphone system. Using both the streamer and DAC of the X1 would also give me a very high quality full-decoding MQA DAC.

[concluded, for now, below]
 

tmallin

WBF Technical Expert
May 19, 2010
355
26
28
66
Chicagoland
#6
Sound Quality

As implemented in my system set up as described above, the Lumin U1 Mini sounds wonderful indeed!

The Auralic Aries G2 has more energy in the lower registers, from midbass up through lower midrange. It tends to sound darker and weightier. It also can often have a larger sound field, especially in terms of projection forward of the speaker plane and envelopment of the listener with phase-manipulated material.

But the Lumin certainly has adequate weight in the lower registers to sound totally natural. Its deep bass is fully the equal of the Auralic's and the entire bass range through lower midrange area sound better defined and differentiated and just plain clearer than the Auralic's.

The Lumin has a bit more energy than the Auralic in the heart of, the midrange where vocals live. This doesn't add unnatural forwardness or projection. It just seems to make vocals sound a bit more "alive" or present. The highs are at about the same level as those of the Auralic, but seem yet more filligreed.

Perhaps at least partially because of the overall tonal balance difference, the Lumin tends to sound clearer and yet lower in distortion than the Auralic. The Lumin also has quite superior depth of field behind the speaker plane, both in terms of rearward extension and specificity of image placement in depth. Its soundfield is more sculpted and carved in space with more three-dimensional images in a more three-dimensional space. The Lumin has superior focus of centered images. Centered images do come out a bit more forward in the stage than with the Auralic, but not unnaturally or unpleasingly so.

The Lumin also has what I feel to be a more "human" or more "analog" sound. There is a naturalness to the way music is reproduced which seems the opposite of "digital" reproduction. You can ease into the sound in a very comfortable way. At the same time, rhythms are infectious, dynamics are unrestrained, and PRaT factors are present at a very high level indeed. Musicians playing well together sound more like real people than just a collection of instruments playing a tune.

Neither the Lumin U1 Mini itself nor the Sbooster produce any audible mechanical noise. And signal-to-noise ratio seems stellar, with extraordinarily black backgrounds, fully the equal of and probably a bit superior to those of the Auralic Aries G2.

I generally prefer the sound of the U1 Mini with its resampling feature turned off. Resampling/upsampling 44/16 program material to 176/24 or 48/16 to 192/24 definitely alters the sound heard through my Benchmark DAC3 HGC. While the presentation often gains an even more open ethereal quality, some focus is lost. In addition, the resampling/upsampling changes the tonal balance of instruments and voices toward a lighter, more treble-oriented (not objectionably bright, however) balance which, in my system, at least, sounds less realistic, less natural. Further, real instrumental detail present in the program often seems cast aside in favor of detail "manufactured" by the apparent change in tonal balance.

Tidal MQA Masters sound better through the Lumin than they did via the Auralic Aries G2. Perhaps this is because the Lumin does "real" MQA first unfolding. The Auralic is not MQA certified, but has proprietary circuitry which Auralic states does the necessary decoding. The Lumin's first unfolding also sounds superior to MQA decoding as done by my Oppo UDP-205 via its balanced analog outputs, and it supposedly does full MQA unfolding, not just the first unfold.

With the Lumin I hear none of the dynamic truncation or odd removal of stick sound on cymbals which I heard via the Auralic or Oppo when decoding MQA material. Via the Lumin, the sound of decoded MQA files on Tidal is fully competitive with that of Qobuz's Hi-Res PCM files. This is not the case with the Auralic or Oppo. Via the Lumin, the Qobuz high-res files have the edge in terms of musical detail reproduction, but the Tidal MQA files frequently are superior in terms of analog-like ease of reproduction and clarity of individual musical lines.

The sound of the U1 Mini's native Tidal, Qobuz, TuneIn radio, and file library functions does get a bit better yet if Lumin Streaming (aka Apple's AirPlay) is turned off via the Settings Options. The effect is not large, but it's definitely there. The difference is usually one of slightly decreased brightness and slightly increased clarity of instrumental lines when Lumin Streaming is turned off.

In this way the Lumin is like the Auralic Aries G2. It's just that Auralic admitted that turning off the non-native streaming functions (AirPlay, Spotify Connect, etc.) aided the sonics of the native functions whereas I do not see that remark in any of the Lumin documentation. As with the Auralic, however, the sonic differences are slight, so small that for convenience of access to internet radio streams not provided through the native TuneIn Radio function, I usually leave the Lumin Streaming/AirPlay function on all the time.
 

tmallin

WBF Technical Expert
May 19, 2010
355
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Chicagoland
#7
For those of you wondering how the unmodified Lumin U1 Mini would stack up against the Sboostered version I'm using, perhaps you need not feel like a second-class citizen. There are those who find well-designed switching mode power supplies (SMPSs) like the one I removed from the Lumin to be just as good for audio devices as linear power supplies, maybe better. See the following discussions by Archimago and John Sau (of Benchmark):

http://archimago.blogspot.com/2019/07/measurements-switching-power-supplies.html

and

https://benchmarkmedia.com/blogs/ap...audio-myth-switching-power-supplies-are-noisy

Of course, if that's so, then why does Lumin use outboard linear power supplies in its more expensive devices? Is it just audiophile perception which dictates this choice?
 

tmallin

WBF Technical Expert
May 19, 2010
355
26
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66
Chicagoland
#8
As I suspected in post #4 above, the problems I had with sorting my audio files totally disappeared once I abandoned inserting the one terabyte USB stick into one of the USB ports on the back of the Lumin U1 Mini. I must say that having additional sorting methods is indeed convenient! But, then, many of you certainly already know that.

Instead, I now serve up my music files from my Dell desktop computer which is part of the same home network as the Lumin. I plug that USB stick into one of the USB ports of my Dell desktop computer. I loaded the Minimserver program Lumin recommends on that computer. After a bit of futzing with my firewall settings to allow the Lumin and my iPad to "see" that computer and communicate with it on the network, the Lumin found my music library on Minimserver right away. It took Minimserver only a couple of minutes to index my more than 15,000 music files, which are all in uncompressed WAV format.

Sonically, the files played back that way through the Lumin app sound about the same as they did with that USB stick inserted directly into the back of the Lumin. However, all the other playback functions of the Lumin--Tidal, Qobuz, Tune-In radio, and other Web-based streaming services--now sound better than they did before--clearer, blacker background, more three dimensional, etc.

I don't claim to understand why these other sources now sound better. But I can't say that I was totally unprepared for this sonic improvement. Others have noted that for best sonics you shouldn't use USB connections as both inputs and outputs of a streaming device. See, for example Steve Nugent of Empirical Audio's comments in his computer audio recommendations at this link. I use the USB output of the Lumin to feed my digital equalizer and DAC so using its second USB port as in input to access my music library may have been causing this lessened audio quality.

Another reason I'm not surprised by the sonic difference is the fact that my prior streamer, the Auralic Aries G2 seemed to have stability problems even just using its USB output. Attempting to add USB access to my music file via that stick came close to totally crashing the software, producing random, inconsistent, and slow response to commands.

I am more and more impressed with the Lumin App. It just works. But, more than that, any problems are quickly addressed by the technical team behind the app (a new update was issued yesterday and it installed without a hitch), and the graphics are very nice and well organized. It's a joy to use. All my music files and streaming services work very well together through it.

Roon may offer a yet-slicker interface than the Lumin App if you need/want one. I've just downloaded the trial version and began to use that over the last weekend. Talk about being able to go down a musical rabbit hole! Roon opens possibilities for musical exploration I never dreamed about before, but I'm not really sure the audiophile in me needs this level of musical inter-relatedness.

Sonically (with the exception of the DSP equalization opportunity Roon affords!), the Lumin App is at least as good if not better in my setup, so the differences so far are purely how the music is organized and inter-related. I probably will comment further on Roon after I get more experience with it. Many music lovers swear by Roon, but already I can tell that it is not really classical music oriented in terms of the "deep knowledge" it offers.

Computer audio is fascinating. The more I play around with it, the more I realize I don't know about it. Not only does it present unprecedented opportunities for organizing, accessing, and inter-relating all your own and much of the world's other music, but it also presents an entirely new and actually much broader array of electronic and mechanical things to tinker with in the quest for the best possible sound from music files.
 

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