Benchmark DAC3 DX

tmallin

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May 19, 2010
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My appreciation for my Benchmark DAC3 DX has only grown over time. No, it is not perfect, but my wish list for its improvements is not sonic, but functional.

I hear nothing "wrong," nothing "missing" from its presentation. Of the DACs I've used, it is peerless in terms of revealing the tonal and spatial differences among recordings, sonic details, and being tonally even-tempered. It never gives the impression of being anything but sonically neutral in terms of tonal balance or the spatial qualities of the recording. It has the blackest of backgrounds and the highest level of audible sonic detail without ever making me feel or hear any edge/etch/overbrightness, etc. which I can reasonably lay at its feet. It is more immune to the quality of cables and sources feeding it than any other DAC I have owned--not totally immune, but the sonic results are not nearly as sensitive to cables and sources as with other DACs I've used.

It's volume control, source selections, and cable driving capability allow it to function as the preamp of my system. No analog preamp is necessary. Benchmark makes other versions of the DAC3 which incorporate analog inputs if they are needed and those analog inputs are never converted to digital when fed through those versions of the DAC3. For me, an array of digital inputs is sufficient, so I went with the DX version.

The DAC3 DX also includes one heck of a headphone amplifier. Even with my very low sensitivity Audeze LCD-4, the sound quality and SPL capability is basically on par with what I hear from my SimAudio Moon Neo 430HA separate headphone amp, a unit which costs 2.5 times as much as the DAC3. Lately for headphone listening I find myself listening more through the DAC3 DX than through the SimAudio. The SimAudio is more laid back with a more relaxed/sweet high end with a "bigger" left/right presentation, while the Benchmark sounds more focused, dynamically punchier (especially in the bass), and involves me more in both the rhythm and dynamic ebb and flow of the presentation. Also, the spatial qualities of the driven headphones vary more from one recording to another with the Benchmark, just as they do when the Benchmark is driving my Janszen Valentina Active speakers. For these results from the Audeze LCD-4s, the SimAudio is set to high gain and the Benchmark is set for 0 dB attenuation from its headphone outputs.

The remote control is hefty and sturdy, not the lightweight plastic variety that one usually sees. The buttons require a firm push to engage, which I like so as not to inadvertently change settings with routine handling. Once firmly pushed, the button controls are utterly reliable with the remote aimed only in the general direction of the unit. The operation of the volume control via the remote is signaled by a flashing pair of lights on the front panel of the DAC3 chassis. Other lights change as the mute or volume attenuation is engaged, or inputs are changed via the remote. The lights on the Benchmark also indicate the quality of the digital signal reaching the DAC, both in bit depth and sampling rate.

The included paper/online manual is fantastic, explaining all functions in great detail with clear close-up pictures where helpful. This is special importance since several functions, such as adjusting the gain for the XLR and headphone outputs, require opening the case and moving internal jumpers. The manual also includes a full set of measurements, the most technical detail for an audio electronics product I have seen. The packaging is also first rate in terms of protecting the unit during shipment and being custom designed for this unit so as to provide that protection without any messy packing materials. Shipping for my in-stock unit was lightning fast and the online ordering process was painless.

Note that my sonic comments are based on using basically the type of cables Benchmark recommends for use on the inputs and outputs of the DAC3--solid pro-audio type cables, nothing exotic or overly expensive. I think the analog output cable type is especially important and I do use the recommended Canare Star Quad L-4E6S cable.

In my opinion, at a current price of just under $2,100, the Benchmark DAC3 DX gives great value for money. Now, if Benchmark wants to offer a new deluxe model, perhaps on a larger chassis, then here is what I'd wish for, but only to the extent that these changes could be implemented without compromising the unit's current sonics in any way:

1. For functions which now require opening the chassis to implement, implement these functions via a remote control and/or chassis push button method.
2. Provide dim and off states for the front panel lights. Yes, the lights are useful for determining status of the unit and it inputs, but the LCDs are bright if you look at them while listening in semi-darkness as I often do.
3. Add backlighting to the buttons and identifiers on the remote control.
4. Add a balanced headphone output.
5. Add additional DAC chips so that the Aux output buss has the same fidelity as the Main output buss. I use the Aux to drive my separate headphone amp. Right now, to drive a separate headphone amp with the same fidelity as the Main output buss, I'd need to buy another DAC3 and use the digital pass through to feed it. Of course, the need for a separate headphone amp is questionable, given my sonic findings.
6. Implement the current digital pass through on a separate coax jack so that enabling that function does not eliminate one of the coax digital inputs.
7. If the chassis is made larger, a dimmable LCD display of all the status functions would be possible to include and the bright lights on the front panel could be eliminated.
8. Add an HDMI input which can accept both PCM and DSD signals. This would make it possible to use the HDMI output on my Oppo BDP-105D (and many other digital disc players) without the need to feed the signal through an HDMI audio de-embedder like the Kanex Pro I use and would also allow the input of DSD signals (rather than PCM) from SACDs from my Oppo.






 

tmallin

WBF Technical Expert
May 19, 2010
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Doubling Down on the Benchmark DAC3: Adding the DAC3 HGC

In the post above, I wish for certain improvements to the Benchmark DAC3 DX, including:

5. Add additional DAC chips so that the Aux output buss has the same fidelity as the Main output buss. I use the Aux to drive my separate headphone amp. Right now, to drive a separate headphone amp with the same fidelity as the Main output buss, I'd need to buy another DAC3 and use the digital pass through to feed it. Of course, the need for a separate headphone amp is questionable, given my sonic findings.

In order to address this issue, I've put my money where my mouth is and have added a second Benchmark DAC3, this time the more usual DAC3 HGC, with one with analog inputs and a Hybrid Gain Control (that's where the HGC nomenclature comes from: analog signals are kept analog through the unit while digital signals are kept in the digital domain until the D/A conversion). Not that I have any analog sources, but . . . . Well, there's where it gets a bit complicated.

In my quest for the best sound from my Audeze LCD-4 headphones, I've sensed that my SimAudio Moon Neo 430HA headphone amplifier should and could sound better than it did driving these phones. That headphone amp sounded better, it seemed to me, before I got the Benchmark. Indeed, with the Benchmark, as I describe above, these phones sound better in certain ways driven from the Benchmark DAC3 DX's own headphone jack than it does from the 430HA. In thinking about this issue, I came to the conclusion that I've been handicapping the SimAudio headphone amp by feeding it (1) unbalanced audio out form the DAC3 DX and (2) feeding it from the DAC3 DX's Auxiliary output buss.

Frankly, if I'd bothered to read the Benchmark DAC3 DX manual carefully before I purchased that unit, I would have purchased the DAC3 HGC in the first place. No, I don't have any analog sources and don't intend to add any. But, no, I don't have any digital sources needing an AES/EBU input either, and don't intend to add any. Still, I thought it more likely that I might add an AES/EBU-output-equipped source in the future than the chance that I might add any analog sources. Also, I figured keeping any analog circuitry out of the unit before the D/A conversion might be a good thing.

The DAC3 DX also solved the problem of how to drive my SimAudio headphone amplifier while allowing the speakers to be silenced without getting up from my chair. The DAC3 DX, with its separate Main and Auxiliary output busses, allows turning the volume down on the Main buss feeding the speakers while simultaneously driving the separate SimAudio headphone amp from the Aux buss. The Aux and Main busses can be separately set to be either variable or fixed level. I set the Main buss to have its output level varied by the Benchmark's volume control and the Aux buss at the Calibrated level to drive the SimAudio headphone amp at a fixed 2.0 volt maximum level. That way, to listen to headphones with the speakers silenced, I just turned down the volume of the DX all the way and used the SimAudio headphone amp's volume control to control the SPL I heard through the headphones. Note that the Mute function of the Benchmark DAC3 DX mutes both the Main and Auxiliary busses together, with no separate muting of just the Main buss available.

Now, with the Janszen Valentina Active speakers, I could have muted the speakers for headphone listening just by getting up and flipping the power switches on the back of both speakers. But, I'm too lazy to do that each time I switch back and forth from loudspeaker to headphone listening. Besides that, if I ever moved back to passive speakers with separate amps, I'd still probably have to get up to turn off the amps. Amps sound better when powered up all the time anyway.

I also could have driven both the SimAudio headphone amp and the speakers from the Main output buss of the DAC3 DX in one of two ways. First, I could have used the unbalanced analog output of the Main buss to drive the separate headphone amp. Second, I could have used a Y-cable from the balanced XLR Main buss output of the DAC3 DX to drive both the speakers and the SimAudio headphone amp simultaneously from the DX's single Main balanced output. The Aux analog output buss of the DAC3 DX does not have balanced outputs, just unbalanced. But either of these methods would still have required me to get up and flip their power switches in order to silence them before headphone listening, then get up again to turn on the speaker power when returning to loudspeaker listening.

What I didn't realize before I bought the DAC3 DX is that, besides the difference in balanced output being available only from the Main output buss, the potential sound quality of the Aux buss is also "compromised" in the way the DAC chips are used in that unit. To quote from the Benchmark DAC3 DX manual:

The MAIN bus drives the XLR outputs and one pair of RCA outputs. The MAIN bus delivers the highest performance because it uses three conversion channels wired in parallel for each XLR connector. The main bus uses 6 of the 8 channels in the ES9028PRO D/A conversion chip. The remaining two channels in the ES9028PRO drive the AUX bus.

Elsewhere the manual also says:

The conversion system in the DAC3 DX achieves a 4.8 dB signal to noise improvement through the use of 3:1 summing on the main outputs. The ES9028PRO D/A is an 8-channel 32-bit converter. In the DAC3 DX, three channels are summed in the analog domain to form the main outputs. The remaining two channels provide the auxiliary outputs.The 3:1 summing also improves the THD. The non-linearities in individual conversion channels are averaged across the four summed channels and incoherent nonlinearities are attenuated by almost 4.8 dB.

These descriptions of what goes on in the DAC3 DX gave me further hope that the sound of the Audeze LCD-4 headphones driven by the SimAudio headphone amp could be improved if the headphone amp could be driven from the Main rather than Auxiliary buss of the DAC DX. But, I was still too lazy to implement this change.

What to do, what to do! . . . My solution was an old-fashioned one: throw more money at the problem in the hope that such extravagance would produce the desired result. And, in fact, in this case that old-fashioned solution has panned out for the best. Not only are the Audeze headphones sounding their best ever, but the Janszen Valentina Active speakers even sound a bit better.

The solution was to add a second Benchmark DAC3, this time the DAC3 HGC. Reading the HGC manual carefully this time before purchase enabled me to figure out that this solution might in fact work. The DAC3 HGC has no Auxiliary analog output buss at all. Instead, it uses 4:1 summing of the channels of the ES9028PRO DAC chip, producing 6.0 dB signal-to-noise gains, rather than the 4.8 dB gain of the 3:1 summing for the Main buss of the DAC3 DX.

Here's how I have things connected now:

1. The digital sources (EVS-modified Oppo BDP-105D for discs and Tidal, Logitech Squeezebox Touch running the aftermarket Enhanced Digital Output software, and the Apple Airport Express) are all connected to the Benchmark DAC3 HGC. The Oppo's HDMI output goes through the Kanex De-Embedder with coax digital cable from the Kanex feeding input D3 of the DAC3 HGC. The Touch's USB output feeds the USB input of the DAC3 HGC. The Airport Express uses input D1 of the DAC 3 HGC, which is a toslink input. The Main balanced analog output of the DAC3 HGC feeds the speaker's internal amps via balanced analog cable.

2. Input D4, a coaxial digital input of the DAC3 HGC, is converted to a digital pass through via an internal jumper change in the DAC3 HGC. This digital pass through feeds input D4 of the DAC3 DX via a coax digital cable.

3. The Benchmark DAC3 DX's Main output buss is set to Calibrated mode for input D4, coming from the DAC3 HGC's digital pass through. This Calibrated mode and selection of input D4 is intended to be unchanging. In this way, the DAC3 DX always sends to the SimAudio headphone amp whatever source is selected by the DAC3 HGC and passed through digitally to the DAC3 DX's input D4.

4. The Main Buss balanced analog output of the DAC3 DX feeds the balanced analog input of the SimAudio headphone amplifier via balanced analog cable.

5. Since any Benchmark remote control controls both the DAC3 DX and the DAC3 HGC, the remote control of the DAC3 DX has been disabled by placing three layers of black electrical tape over the DAC3 DX's remote control sensor. This is necessary to prevent the DAC3 DX from responding to remote control signals meant for the DAC3 HGC, which is the unit selecting sources and changing the volume going to the speakers.

6. With this connection, I can also use the Mute function of the DAC3 HGC to silence the speakers without turning the volume all the way down. The output level of the digital pass through of the DAC3 HGC is not affected by the volume or mute functions of the DAC3 HGC.

Complicated, yes, but still very compact, as shown in the attached pictures. In addition, the SimAudio Moon Neo 430HA headphone amplifier, now really shines, besting the sound of the Audeze LCD-4 driven from the Benchmark's own headphone jack (still no slouch!) in all ways. The speaker sound gains an uptick in performance as well, with yet greater focus, better imaging and staging, yet blacker backgrounds, and yet stronger and simultaneously better controlled bass.

IMG_5479rotated.JPG View attachment 35390 IMG_5480.JPG IMG_5482.JPG




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tmallin

WBF Technical Expert
May 19, 2010
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Benchmark HPA4 Headphone/Line Amplifier

At AXPONA 2018 in Chicago I got to see, hear, and play around a bit with Benchmark's forthcoming HPA4 Headphone/Line Amplifier. I liked it so much I've pre-ordered one. For additional information about the design of this new amp, see Benchmark's Application Note about it. That note analyzes most of the common methods of controlling volume in an audio system. What some may think is the most basic function of a preamp is also one of the most vexing in terms of achieving true transparency.

Adding this to my system will allow me to dispense with the DAC-3 DX whose sole purpose is to feed balanced analog output signal to my SimAudio Moon Neo 430HA headphone amplifier. From what I heard of the new HPA4 driving Audeze 'phones, the SimAudio will also be history. The new Benchmark sounds absolutely awesome driving Audeze cans. Everything is just so fleshed out, clear, and driving, yet without any brightness/glare/grit at all, just like the Benchmark AHB2 amps which drive my Harbeth Monitor 40.2s. This makes sense since the new HPA4 uses the same THX Achromatic Audio Amplifier technology embodied in the AHB2 power amp.

I thus envision feeding the balanced analog output from my Benchmark DAC-3 HGC to the balanced analog inputs of the HPA4, with my Audeze LCD-4 headphones plugged into the 4-pin balance headphone output of the HPA4, while the balanced analog outputs of the HPA4 will feed the balanced analog inputs of the Benchmark AHB2 power amps. A single remote control operates both the DAC-3 HGC and HPA4. The headphone and main outputs of the HPA4 are separately mutable. This would allow the HPA4 to replace both the DAC-3 DX and SimAudio Moon Neo 430HA in my system.

Part of the appeal for me of Benchmark's electronics is their unmatched quiet. The combination of absence of noise with extremely low distortion leads the industry. This is audible as increased audible detail of all kinds, whether spatial, tonal, or transient without the need for any frequency-related tailoring of the response to artificially boost detail. Up to now, Benchmark has recommended directly driving the AHB2 amps from it DACs in order not to compromise this quality by adding a higher-noise/distortion component in the middle of that chain. With the HPA4, however, Benchmark is now claiming:

The HPA4 is the perfect complement to the Benchmark AHB2. It may be the only preamplifier or line amplifier that exceeds the signal to noise ratio of the ultra-quiet AHB2. This means that the HPA4 will extract the full performance of the AHB2. In contrast, other preamplifiers limit the system noise performance because they cannot match the SNR performance of the AHB2. The HPA4 is the only line amplifier/preamplifier that we recommend inserting between a DAC and the AHB2. The HPA4 can be inserted between a Benchmark DAC3 and AHB2 without degrading the system noise performance. With the HPA4 inserted, the DAC3's 32-bit digital gain control is replaced by the HPA4's more-resolving fully-analog relay gain control.

​We shall see. The HPA4 is scheduled to ship in June.
 
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Folsom

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Oct 26, 2015
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Nice. That's the way to do it. Use an Oppo for a CD transport, instead of blowing more money on entirely pointless more expensive transports. The Benchmark products are very good. Their designers are very smart, and not completely "by the book".
 

cjf

Well-Known Member
Nov 19, 2012
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I've been waiting a loooong time for a device like this. If this thing works as advertised and can function as a proper Analog PRE-AMP, even in a non Benchmark system, then I suspect it may just turn the "High End" Pre-Amp industry on its ear.

Man, I'm so glad I didn't pull the trigger yet on that 5 $$ digit Pre I was intending to pick up next month :cool:
 

tmallin

WBF Technical Expert
May 19, 2010
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I just took delivery of the Benchmark HPA4 this past Monday. I got it set up in the wee hours of the next morning. Mechanically and electronically, it works as advertised. Once all the connections "break in" (usually about a week after I treat the connections with Caig Deoxit Gold 100L during set up) and I then have a chance to seriously listen and compare the system's prior performance with the performance of the speakers and headphones pre-HPA4, I will start a new HPA4 thread. My first sonic impressions are extremely promising.
 

ksalno

Well-Known Member
Mar 29, 2015
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111
Tom,

I have a DAC3 HGC and have grown somewhat frustrated by the inability of the DAC3 to handle DSD128 or higher. Almost all newer DACs that I see, if they handle DSD at all, are capable of handling at least DSD128, if not DSD256. In your discussions with Benchmark, is this something they intend to address or is it their choice of the Sabre 9028Pro that is limiting this?

Karl
 

tmallin

WBF Technical Expert
May 19, 2010
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Sorry, but I have never discussed DSD decoding with anyone at Benchmark. The only DSD recordings I use are those emanating from SACDs, which are DSD64, not even 128.

I have nothing against pursuing the few high-res DSD recordings that are out there. However, I seriously doubt that this is a genre that will ever get much more traction than it has already. Benchmark is reasonable in sticking with PCM. That's the way most recordings are made because most pro-audio equipment uses PCM processing, not DSD.

My perception is that the real problems with recordings are not in the digital encoding technology, but in the recording technology. Poor microphones, poor microphone deployment, too many microphones, too much studio processing, too much compression and digital effects, intentional unnatural equalization, etc. I'd much rather listen to a 44/16 320 kbps MP3 made with fine recording technique, than the highest resolution decoding of a multi-miked, highly compressed, made-with-smiley-face-EQ disaster. The MP3 will sound much more natural than the high res one.
 

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