Thanks Ted for your detailed response. How is the pre-amp in the Wyred4Sound?
Not to dive too deep into technical stuff (as there are articles out there that cover this) but here's my experience:
The Wyred DAC 2 is nice in that it attenuates in the digital realm, so there's no op amps, pots, etc in it to control volume. Here's the catch. Any DAC that attenuates in the digital realm will shave resolution. With CD sound, this isn't a huge deal. The DAC is 32 bit, and CD's are 16 bit. So the DAC has quite a bit of room (16 extra bits) to attenuate volume without affecting resolution. But when you start looking at high res downloads, which are 24 bit, you have much less room to attenuate the volume. I'm sure this is likely the same for DSD.
Not to get too far off topic, but how much attenuation you need depends on how loud you like to listen, your amp's input sensitivity and power rating, and your speaker's sensitivity.
With that said, I listen at quite modest volumes. I couldn't attenuate the volume of the DAC enough without beginning to eat away at resolution. I was even using Harrison Labs -12db attenuator plugs at the amp input.
I ended up getting a Wyred STP SE, and the rest is history. I can run my DAC at full resolution regardless of source material. Not to mention, my system took a turn for the better in terms of overall musicality, drive, detail, listening pleasure, and flexibility. The STP SE is a fantastic piece of equipment, as is the DAC 2.