DACs Galore and Expectation Bias

nc42acc

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Since the addition of the Aurender N10 in my system I have been wanting to do a subjective listening test of the DACs I have in my possession. The reason the N10 is so important is it drives all its outputs simultaneously. Of course I need to use two different output types but I interchanged them through my evaluation. The two primary outputs I used are USB and AES. The DACs evaluated are as follows. Schiit Yggdrasil, Gustard X20, Auralic Vega, Line Magnetic LM 502ca (tube section) I level matched each DAC, the Gustard X20 has higher level outputs, as I only listened to two per session. All listening was done via balanced XLR outputs using Neotech NEI-2002 interconnects with Furutech XLR plugs for each DAC. The rest of the system is as follows, ARC REF5SE, Anodyne Tube/MosFet hybrid mono amps, Von Schweikert VR5 Anniversary MKII. Preamp to amp cable is Luminous Audio silver reference, speakers bi wired with Bren1 Oasis, I used two Pangea AC14 SE MKII power cables on both DACs tested.
I think I have a reasonably resolving system and trust my ears to hear differences. Guys you could throw a blanket over all four DACs and would challenge the average person to hear the differences. It is amazing they ALL have basically the exact same presentation, very minor differences between them I will list below. Presentation I mean if the recording has ambience you hear it, if the vocals are pushed back this is what you hear.The REF5SE allows me to switch via the remote with absolutely NO lag or change in material, instant switch. I believe in this crazy business when you hype a product and read all the press you build that expectation bias, then factor in the time to remove a component from your system to add another or worse yet rely on your audio memory of days or months past and even worse in a different system. Do we hype ourselves into hearing what we want to hear? I know I am comparing a small slice of the market all competing in the same price range but my results below are what is shocking.

1. Gustard X20 Retreives the most detail and ambient clues of the bunch. This is where this DAC shines is in the minute audio details and depth resolution.

2. Line Magnetic LM502ca Tube magic is all I can say, using the tube output section on most recordings this DAC imparts a euphoric character that is very pleasant. Also a slight extended soundstage.

3. Schiit Yggdrasil Extremely close to the X20 except it rounds off the leading edges of transients slightly giving it a slight smoothed character. This one was the hardest to evaluate against the X20 because it was so close.

4. Auralic Vega The Vega just omits the micro details, they are just missing. The little nuances of a live recording go missing, the little aural clues that help you hear the sense of space.

Again these are small details I list above. I could say I would be perfectly happy with all of the top 3 if I weren't so OCD on presentation and the small details. Hopefully I am going to jump a step up with maybe a Berkeley Reference or MSB Analog DAC soon. I hope they can break above these DACs in sound quality and resolution. Right now I have two DACs in my system, the Gustard X20 because I have a large DSD collection and the Line Magnetic because tubes make everything sound better and it only does PCM.
 

Rodney Gold

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Anything I can AB I do , level matched if possible
I have and do AB various things

DRC filters and target curves
Dacs
Bass setups using my 4 subs and DSP
SPDIF vs AES vs optical
CD vs rip
Tidal vs Rip
and a whole lot more

Mostly seamless , mostly in the digital domain .. no blind testing tho I sometimes rope my wife or kid in to switch , often gives me a great insight into the product.. not a scientific quest by any means and mostly to hear what I prefer

At any rate , with respect to expectation bias .. I have fooled myself many times , like thinking im messing with a filter and hear my changes on the fly only to find the filter was bypassed...stuff like that
 

Purite Audio

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I am surprised the Auralic seemingly lacks resolution, I believe it is an over sampling design, the Schitt is R2R which can sound different and as you mention a valve output can add pleasant distortion.
I would be interested to hear your thoughts on the MSB ( R2R I believe) and the Berkeley which again is over sampling.
Keith.
 

nc42acc

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Keith the only two using the exact same DAC chip is the Gustard and Auralic. It is amazing how close all these sound when doing an instant AB test.
 

Purite Audio

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Keith the only two using the exact same DAC chip is the Gustard and Auralic. It is amazing how close all these sound when doing an instant AB test.
Marty hi, I am not really surprised, a dac is a digital to analogue converter , it should neither add nor subtract.
Some manufacturers deliberately tailor the response, I guess this helps in comparative demonstrations.
Keith.
 

asiufy

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Just out of curiosity, what settings did you use on the Vega? Did you leave it powered on for at least a couple of hours before A/Bing?


cheers,
alex
 

nc42acc

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Alex I left it powered up for over 24 hours and used the exact clock settings. Only used PCM as the Schiit and LM are not DSD capable.

Just out of curiosity, what settings did you use on the Vega? Did you leave it powered on for at least a couple of hours before A/Bing?


cheers,
alex
 

scouter

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Marty,
Do you think the ARC "equalized or generalized" the sound of the DACs with its specific attributes? I know we have talked offline, and it seems DACs reveal their character more w/o a preamp and additional interconnects in the chain.
 

nc42acc

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Barry I know for a fact the REF5SE generalized the group to a certain degree. The Gustard X20 sounds fabulous driving the amps direct but it and the Vega are the only two with volume controls.

Marty,
Do you think the ARC "equalized or generalized" the sound of the DACs with its specific attributes? I know we have talked offline, and it seems DACs reveal their character more w/o a preamp and additional interconnects in the chain.
 

esldude

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Did you level match for these comparisons?
EDIT: Oops poor reading comprehension on my part. How did you match levels?

Also, just a suggestion, a good way to see if there are differences in frequency response via listening is playing some pink noise and switching between them. Even small response differences will jump out this way. Gentle small differences in response can manifest in a number of different ways that seem like something else.
 

nc42acc

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I level matched by ear that there were no discernible loudness differences when switching inputs on the preamp. On all the comparisons I needed to reduce the output of the X20 to level match, not sure if this hindered it in the comparison. I know this is not the best method but for me this was a fun and informative test.

Did you level match for these comparisons?
EDIT: Oops poor reading comprehension on my part. How did you match levels?

Also, just a suggestion, a good way to see if there are differences in frequency response via listening is playing some pink noise and switching between them. Even small response differences will jump out this way.
 

jkeny

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Marty,
Do you think the ARC "equalized or generalized" the sound of the DACs with its specific attributes? I know we have talked offline, and it seems DACs reveal their character more w/o a preamp and additional interconnects in the chain.

Agreed, preamps are the biggest offenders in masking differences
 

esldude

New Member
I level matched by ear that there were no discernible loudness differences when switching inputs on the preamp. I know this is not the best method but for me this was a fun and informative test.

I don't intend to be highly critical. Matching by ear is done so many times. And it simply isn't adequate for a really, really good comparison method. Your ear will match to about a db, and maybe a little better. As little as .2 db difference will make things sound different just because of the level.

You might well go back and do the same comparison, and randomly shuffle volume by .25 db and come to different conclusions.

If you wish to do something like this in the case of DACs, a multimeter, a 1khz test tone at -20db and match to within 1.2% of the same voltage. You can measure at the speaker posts.
 

nc42acc

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That would have taken the fun out of the comparison with the extra work. I don't take your comment as critical because everything you said is true. What I came away with my little test was the "flavor" of all these DACs are very close and I didn't uncover any earth shattering differences. Thanks for your reply.


I don't intend to be highly critical. Matching by ear is done so many times. And it simply isn't adequate for a really, really good comparison method. Your ear will match to about a db, and maybe a little better. As little as .2 db difference will make things sound different just because of the level.

You might well go back and do the same comparison, and randomly shuffle volume by .25 db and come to different conclusions.

If you wish to do something like this in the case of DACs, a multimeter, a 1khz test tone at -20db and match to within 1.2% of the same voltage.
 

jkeny

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After a fresh set of tubes in the REF5SE it is amazing how transparent it really is. The bass is a little better using the REF5SE.

What playback software are you using?
Can you try using the vol control in the software & bypass the preamp, altogether - just as a test of how transparent the preamp really is?
 

nc42acc

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I am using an Aurender N10 for music duties, the X20 will drive the amps direct as it has a volume control feature. I listen to a few songs with the X20 connected direct then place the preamp back in. Before the new tubes, softening and muting of details, after the new tubes more of a 1 to 1 comparison. Hope this makes sense.

What playback software are you using?
Can you try using the vol control in the software & bypass the preamp, altogether - just as a test of how transparent the preamp really is?
 

khonfused

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We've just done a similiar comparisation this weekend.

Two Metrum Pavane, one original, one with modified transformers and a soekris dac. All sounded pretty much the same, with a little more here and a little more there between them.

Only after we added a Lampizator Big 5 to the game, there was a discernible difference in the presentation. Finally there was music in the room not just sound.

Noone had heard a lampi before and everyone was very impressed.
 

Argonaut

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Barry I know for a fact the REF5SE generalized the group to a certain degree. The Gustard X20 sounds fabulous driving the amps direct but it and the Vega are the only two with volume controls.

From this, and other posts it would seem that the Gustard X20 punches above its price point.

Marty, If you are able to source an NOS General Electric 6550A you will find the stock Sovtek 6550 really does the Ref5SE no favours at all.
The new ARC Ref6 is also an evolution in terms of neutrality, should you wish to remove a degree of 'generalisation' from your system.
 

nc42acc

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I agree, a true bargain but at the cost of the unknown if future issues arise. I have not read anyone needing repairs and how this would be handled.

I am using a Tung Sol 6550 in the REF5SE and it did make a noticeable difference. Seems to run a little hotter with the Tung Sol.


From this, and other posts it would seem that the Gustard X20 punches above its price point.

Marty, If you are able to source an NOS General Electric 6550A you will find the stock Sovtek 6550 really does the Ref5SE no favours at all.
The new ARC Ref6 is also an evolution in terms of neutrality, should you wish to remove a degree of 'generalisation' from your system.
 

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