What did a good 10 MHz clock do for your Gustard R26?

@kairosman I'm starting to suspect I have a bad unit. This is my second attempt to purchase the R26. The first one was very dark to the point of sounding broken. This one is better but still soft in the top octave, and the problem with imaging is very curious (I get fantastic imaging on other DACs). I have about 100 hours of burn-in on the R26 so I'm going to give it another 100 hours.

@kairosman I'm using custom cabling (interconnects, power cords, USB cable) by the same guy who modified my x20pro... it's very good stuff. His friends in the N.J. Audio Society say it compares favorably to multiple-$1000 commercial stuff, but I've never heard anything other than Igor's cable except for low-end Cardas and such. The "slow" filter sounded best for detail and microdynamics. I didn't like NOS much. 

When I refer to imaging I'm actually talking not about my headphones but about my humble speakers... Spendor S3/5. They have great imaging with my modified Gustard x20pro, in terms of the spooky realistic sense that you can face the direct source of sound and pinpoint its location in space. With the R26 the images tend to exist in either left, center, or right, and not be stable. The sizzle on a violin might seem to come from a different place than the body of it. 

The headspace of the R26, with headphones, is decent. I like a sense of open sound when I'm using headphones, i.e. that the boundaries of my head aren't precisely limited, and I get that with the R26. 

What my R26 does really well is soft music, like the fade to silence (or fade up from silence) of a reed instrument. But in general it seems too soft in the top octave.. it requires careful attention to pick up on details. It doesn't grab me like the x20pro. 

Right now, it's playing pink noise through my relatively new LCD-X, so we'll see how they both sound in a few days when it reaches 200 hours.

@audphile1 You're talking about my R26 right? Mine doesn't seem to match the descriptions of others' R26s. Like the imaging. I suspect mine is broken.

I got a Gustard 10 MHz clock, the $750 or so model, from Amazon, could return. After an hour of warmup of the clock (the R26 DAC was already warmed up), I hear an improvement in extension and tonal balance, more midrange where there seems to be an upper midrange recession in the stock R26. But it's a small difference. Call it one step of difference. I would want about 5 steps of difference to be worth $1000 (The Gustard clock plus Gustard clock cable plus tax). I don't think I'm keeping either the clock or the R26. Not sure what I'll do. Maybe just go back to previous DAC (a modified iFi iDSD Nano, surprisingly good after mods). And wait. Maybe try the Denafrips.

@audphile1 I suppose it's possible, but if my system has a characteristic tonal balance, why would it be too dark on one DAC and too bright on another? 

But curiously enough, a lot of my system is modified or custom by the same guy who modified the Gustard x20pro. He did my power conditioning (which is based on parallel capacitance concentrated on my system circuit but also distributed throughout the house), my power cords, interconnects, headphone, and USB cable, and modified my headphone amp. Also speaker cable. My Aurender N100 is stock and I've found that greatly improves any DAC it's feeding compared to my previous mini PC. Obviously I really like the sonic character of Igor's work - very extended on top without being bright, deep musical bass, great dynamics (micro and macro), musical details, etc. 

My speakers are stock - Spendor S3/5, and so is my B&K ST120 amp (from the 70's - great amp - mine is excellent condition and low use). 

As far as what parts of my system affect tonal balance, the headphones are the obvious culprit. I have obtained loans or second hand purchases of several headphones and more will be here soon. I really want to give this a chance before I return the R26. 

What I haven't mentioned is that the modified X20Pro stimulates some kind of resonance in my left ear that has something to do with my tinnitus. Certain pitches sound like they've hit a high-Q resonance. Very odd. I'm going to see an ENT about it. For some reason the modified Gustard stimulates the resonance like crazy, which became more obvious when feeding it from the Aurender, while the modified iFi iDSD doesn't stimulate the resonance at all. And the R26, only a little bit. I want to keep the Aurender as it's so promising, and Igor agreed to trade the X20Pro for future work. So my goal is to match the Aurender with some other DAC that doesn't stimulate the resonance. Oh, the PS Audio doesn't stimulate the resonance.

Thanks for your feedback. I'm sorry I made it so complicated. But I have patience. It's been fun to try a lot of stuff - very educational for my ear. 

@audphile1 

While I do recognize that my system might have some kind of "signature" as a whole that is obscuring these components, I've had a very good experience with Igor's mods. I started with just his power conditioning (but all stock components at the time). It made my system more extended on top and more musical by quite a lot. In particular it made things more extended by not brighter. Everything he's done since has built on that. I've carried some of his modified components to other people's systems and they bring similar qualities. Like, a long time ago when I still used CD I brought his modified PS Audio Lambda II to a friend's system and it improved the extension without making the system brighter. I've been in contact with folks in the New Jersey Audiophile Society who use his cables rather than the $5000 cables they could easily afford. He mainly takes moderate priced equipment and brings out the potential - so for instance my headphone amp is a Chinese 12AU7/FET zero-feedback design that comes with a SMPS ($100 new!). He replaced all the parts, added shielding through ERS fabric, added damping, and designed a LPS. Many people in the headphone community praise the concept of 12AY7/FET designs, so it's not surprising how good it is.

With the PS Audio DAC, I'm feeding that by a stock Aurender through Igor's USB cable. Tell you what, I'll replace that with a stock USB cable and test it. Then everything will be stock components except the headphone amp. I'll try it with several headphones through their stock cables. Let's see if it changes the tonal balance or component signature.

@audphile1 Whoa... went to an iFi USB cable (maybe $150 when I bought it 7 years ago) and the brightness in the PS Audio is gone! The strangeness in the bass is gone. It's still a bit bass-light compared to the two Gustards I've had in my possession, but it's much closer to something balanced. It's also less exciting, less microdynamic, less resolution.... but it suggests that I could look for a USB cable with all that resolution, and also the correct tonal balance to boot. Or perhaps drive a D-D convertor through my original USB cable and then drive the PS Audio via coax or something else. 

Huh.... 

I got a hold of a Cardas Clear USB (the top of the line Cardas USB, $450 new) and it works beautifully with the PS Audio. Good resolution, beautiful timbre, and all the bass and brightness problems are solved.

In the previous comment I mentioned an iFi USB cable. That was okay, but after listening for a few hours, it was clear it lacked beauty of timbre and it was grainy on piano.

@audphile1 I did put Igor's best PC on it. The members of the N.J. Audiophile Society tell me it can compete with $5K power cords. Of course this might be introducing Igor's signature again, but I don't think so, because the weirdness all went away with the USB cable switch. 

I listened for a while through two different headphones -- LCD-2 (pre-fazor) and 2021 LCD-X. The LCD-2 is dark, and not a good match for the PS Audio.. it just sounds rolled-off with this combination. But the LCD-2 has a very beautiful midrange, and that came through clearly. I also listened to the PS Audio on speakers and noticed the extraordinarily beautiful midrange and deep musical expression - and like you say, it does require attentiveness on the listener's part, because the PS Audio isn't exactly "grab ya by the collar."

I then listened through the LCD-X, which has a much better overall tonal balance, something generally true of Audeze's fazor headphones. The sound was more interesting and attention-grabbing with the highs no longer rolled-off. But unfortunately there wasn't as much musical expression. The fazor LCD-X has a less beautiful midrange than my LCD-2. I couldn't go with the LCD-X for my long-term listening.

I then switched to my Gustard R26 with the C26 clock. The sound was much more lively and a better match for the LCD-2. In testing the PS Audio and the Gustard, I listened to Maria Schneider's "Walking by Flashlight" for big band, which builds to a climax on a beautiful, very rich/complex chord near the end. The PS Audio emphasized the beauty of this chord. The Gustard emphasized more the climatic nature of it, giving a better sense of shape and finality to the piece.

Because the Gustard is a better match for the LCD-2 (and at this time I don't want to start a whole new search for the perfect headphone), and because I find it more important to make climaxes exciting, I think I'm going to go with the Gustard, which by the way is much improved with the Cardas USB and the C16 clock. I started this thread complaining about the Gustard R26, but it seems pretty resolved. It still needs more oomph, especially in quiet music. My goal is to make quiet music, and sudden pianissimo, as captivating as loud music. (Something true of live instruments.) Maybe a better clock or clock cable.

I love the PS Audio DS Dac's beauty and musical expressiveness. If I could find the right headphone with it, something more balanced than my LCD-2 yet with an equally beautiful midrange, I would go with the DSD no question. I've just run out of time in all this searching.

The Gustard C16 external clock has an OCXO with its own power supply. The R26 has a crystal but not at the level of an OCXO, and it's rare to find a DAC with a separate power supply for the clock. That's part of the benefit of an external clock.

I may have changed my mind. You should probably ignore me because I keep changing it, but I listened to another DAC this weekend (the Denafrips Terminator 1), and tried another USB cable between my Aurender and each of my DAC options. I also considered that whatever I do I'll probably have this technician friend (Igor in New Jersey) modify the DAC, and in the case of the PS Audio he can do the well-known transformer and VOCM mods, which will probably increase the resale value as it's well regarded. I decided that the PS Audio has many strengths (such as faithful/beautiful timbre and musicality) and its only weakness is a bit lacking in oomph and resolution compared to the Denafrips or my previous DAC, the modified X20 pro. Well, Igor can fix that. The R26 and Denafrips had more weaknesses with no guarantee they can be fixed. So I think the winner at this point is the PS Audio! And off to the shop to get the transformer and VOCM mod, plus a power supply component upgrade. Anyway that's the plan. I keep changing it, but I'll know for sure at least by the time the R26 has to be returned to Amazon.