This is not entirely related to PS Audio products but I think I’m going to need an expert to solve it and this forum seems to have some very experienced people.
My DAC for the past 6 years has been a modded Gustard x20pro. I just bought a Gustard R26 (stock) and a PS Audio DirectStream Mk 1 (stock).
I also just bought an Aurender N100 to feed the DAC.
For a long time with the Gustard x20pro I’ve been noticing a resonance in headphones. Piano notes (or wind instruments) around C5 (C above middle C) really stick out, like a high-Q peak in the loudness and blurring of the sound. It’s especially noticeable in close-miked jazz.
However it hasn’t been really strong. Then I added the Aurender to the system, replacing my Win 10 mini-computer, and the resonance became much more bothersome. In fact it was all but impossible to enjoy certain kinds of music such as choral or close-miked anything.
Then I hooked up the DS Mk 1 to the Aurender, and there’s no resonance!
To summarize:
Aurender → DS Mk 1 : no resonance
Win 10 → Gustard x20pro: mild resonance
Aurender → Gustard x20pro : pronounced resonance
The Gustard x20pro has been modified with bypass caps, damping, and carefully applied grounded ERS fabric strips. I never heard it stock so I don’t know if the resonance came after the mod.
I created a file with a swept sine wave, moving at 1 octave per 15 seconds, and listened in each of the above configurations. I did not hear any high-Q resonance in any of the configurations. The volume of the tone went up and down as it crossed various frequency rages, as I would expect it to follow the ear’s sensitivity, but there were no sharp peaks. The only difference: there was a lot more bass with the Gustard compared to the DS Mk. 1.
But when I play synthesized piano tones into the Gustard I can easily hear a high-Q resonance right around C5.
Huh? I don’t know how to make sense of this.