As an aside, as part of the Naim Roadshow I went to last week they gave us the opportunity to listen to their new DAC in a few different ways.
One was the USB (via an iTouch using WAV's), one was from the new CD2XS (via SPDIF BNC) and finally from the HDX (SPDIF but not sure of the connection)
The USB was by far the "least best" sounding. The HDX was a definite improvement but the CD2XS was excellent.
Naim ND5 XS, nDAC, XP5 XS, 202, HC, NAPSC, 250.2, B&W 804s.
AVR350, B&W HTM4, Gallo.
Samsung, Oppo.