"...MUSES01 now. Tested a pair of these in my DAC output, in my main home setup, replacing two pairs of AD797BR opamps--my reference chips up to now--feeding my tube headamp. Interestingly, the first second of the first song I played, I noticed the difference in sound quality with the AD797, but I also noticed no change in sound "color" or "flavor". What does this mean? Well, simply that the MUSES01 is a better opamp than the AD797 in that position, but that's it's just as neutral, which is both good and what I'm looking for (last thing I need is a "colorful" opamp in my DAC like the OPA627...).
The sound is nicely balanced throughout the whole frequency spectrum--if anything, I find myself expecting a tad more bass out of the box, but I'm pretty sure that will solve itself in the first few hours, you know, brain burn in-- with no frequencies dominating the sound. I am hearing more details than with the AD797, better defined, both spatially and in resolution; the soundstage isn't particularly large as I've read (it is a little larger and higher than the AD797, but not deeper), but very 3D-holographic sounding with pleasantly realistic instrument placement and separation. No particular wetness here, apart from what the tubes add in my setup; just a neutral 3D ultra-detailed sound: a better-made AD797 really... I'm surprised by how similar these chips sound--or don't sound actually, since they're so neutral...
Anyway, I will "monitor" the evolution of the opamps in both setups, and report back when my brain has burnt-in lol.