What is the best sounding DAC at $2000-$4000?

Almarg: Thanks again but I couldn't find anything. I'm using PurMusic for playback. I went through PureMusic's menus in "preferences" and couldn't find anything about buffer size. I'm not that knowledgeable about computers and software. I don't want to be a pain here, but can someone describe it step-by-step?

Can't go wrong with the PWD II. It sounds great and has received excellent reviews, one can get significant discounts or buy used here on Audiogon.
Streaming with the Bridge is simple and sounds better than most USB solutions. Paul McGowan is one of the good guys in the industry seeking to provide great sounding equipment at reasonable prices. PS Audio is to be commended.

The new NAD M51 DAC. I have it, it sounds wonderful to me, can act as a preamp and has a variety of inputs. Has sigle ended as well as ballaced outputs. Sterophile did a review of it recently, if that interests you. Costs $2000.

I would just like to thank everyone and at $2000-$4000 I did try several dacs and finally bought what I considered the best match to my system. I would like to say that I really appreciate all the advise.

Well Tamale what did you end up with???