Welp, for those interested, I went in a rather totally different direction. Originally, I bit the bullet and went the Denafrips Terminator II+ 12th. Honestly, I wasn't impressed. It sounded glassy, and the pushed back vocals just was a bit too much. I tried everything - and I mean EVERYTHING. All the settings, combinations of settings, different cables, different preamp, Denafrips top preamp, RCA, XLR, I2s - all of it. I tried the new firmware (worse). I tried USB. I tried about 4 different sorts of cables for each input and output. I tried a solid state amp. I tried a tube amp. I couldn't figure it out. I tried different power sources. I tried a power conditioner. I tried fucking rewiring the electrical to a dedicated outlet (which mattered more than the rest, and was considerably cheaper than most everything). I tried streaming from my computer, streaming from a Wiim, steaming with an iFi, streaming from a Sonos, streaming from an Aurender, streaming with downloaded FLAC, with CD, with WAV, with Audirvana on/off, Tidal, Qobuz, and Spotify. Nothing. I added that top-end schiit equalizer. Garbage. I was totally at a loss. Devastated, I went back to my Topping D90MQA - which was fine, but just fine - better than the Terminator to my ears, but just fine.
My partner took me to D.C. as a surprise, and, while she knows NOTHING about audio, chose a high-end audio store just outside of D.C., and, I remember getting out of the car with the biggest smile saying, "You're gonna make me spend some money, aren't you?!" And, oh boy, money I did spend. I wound up with a Synthesis A40 Virtus tube amp + DAC. About $8k. I listened to everything at the shop. . . for 2 damned days, and about 10 total hours. Frankly, was BLOWN AWAY by Synthesis. The dealer was pairing the amp + DAC I bought with a pair of tiny, TINY little bookshelf speakers (British, but I can't for the life of me recall the name, at the moment - ProAc, I think. They were super tiny). Something that was like 9" high and like 5" across. I mean tiny. And the (rather large) room was FILLED with sound I'd not heard in 20 years. Thick, juicy, vocal forward, room filling, and no loss in detail. Traded my Denafrips. Traded my Wilsenton. Traded my Classe' solid state. Got a Sonos (which is what the dealer used) and the Synthesis A40 Virtus, and couldn't be happier.
It's been 5 or 6 months, and I'm happy enough that I've not even considered anything else. I can finally, finally, FINALLY listen for as long as I want without an ounce of fatigue, and even bad recordings sound better than they should. And the good stuff (stuff like Billie Eilish that, even though I don't normally care for that sortof music but it's just recorded so damned well) sounds absolutely tear-jerking.
I know, one wouldn't think an integrated chip DAC (especially in a tube amp) would even be a good idea let alone sound good, but I can't find anything that sounds better except a bigger Synthesis Amp. It's wild, but, finally, I'm happy.
The setup is now super simple:
Sonos/Qobus
Cardas Clear SPIDF
Synthesis A40 Virtus
Wilson Duette II
done.
Strange, I know. It still doesn't make sense to me, either. Some will say it's the Cardas Clear (as it was $750), but I can tell you, using a basic $150 USB coming from my computer sounds basically the same.
Anyway, let the arguments and nay-saying ensue. :)