Second the EAD DSP 7000 Mk. III. Very smooth presentation, not at all "in your face" but not harsh or straining. Super high quality build & parts, which would bode well for purchase used. Retailed for $2500 in another era, but I've seen them advertised at dirt cheap prices on this site.
The most recent version of the Proceed DAP (Madrigal Audio) is a nice-sounding unit with HDCD, and accepts balanced or single-ended input and outputs. I believe it is still a current model @$2,ooo, but is sold used in the $600-$700 range.