You've done a really nice job on that DAC and it actually measures quite respectably for what it is. Well done.I don't identify with the term audiophile any more, I am in this thing for the music, and I like to build shit. If the shit I build makes the music more fun and engaging to listen to, that's a plus. But obsessing over "the timbre of a violin" or the "stridency of the highs" is not my thing. When I finish prototyping something, I listen to it and it is categorized as "good" or "bad" based on whether or not it has me vibing with the music. I don't listen to audiophile recordings, I listen to the music I like, even if the quality is crap. If you can break the cycle of audio nervosa and instead focus on the music, the enjoyment of this hobby goes up substantially and you can reach contentment, you might even be suddenly blown away by the quality of the gear you own, in my experience anyway.
WRT not identifying with audiophiles, 100% agree.
WRT PCM63, those DAC's can sound *really* good. I think I actually have at least 2 x original K grade floating around used in old projects here.
WRT best I-V for PCM63, my recommendation is run DAC into a grounded base stage BJT with collector cascoded into cathode of a tube. Run *lots* of current
and it can sound staggeringly good.
Lastly, if you are using Jlsounds III for PCM63, this may be a slight compromise because LE is reclocked inside CPLD. Might be worth trying to re clock LE OP
directly from master clock but I have not done this or looked into it, don't use PCM63 anymore.