> I've had multiple of these and some of them have tons of EM noise, which is very obnoxious.
Ah darn yup! If there's one thing I'd expect from these is to not be noisy! FWIW I'm using a CambridgeAudio DAC and, well, CambridgeAudio is supposed to be a good brand when it comes to audio stuff (amp is CambridgeAudio too).
> It looks like these start at $250? I'd expect them to work well.
Price inflated, like the price of nearly everything. I paid mine 150 EUR back in the days (still not cheap but not either the 4 digits high-end audiophile stuff).
The thing is: you want thing to work fine from Linux's side and in my experience USB Audio on Linux just works.
I'm sure there are other brands/models at reasonable price points.