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

Easily the PWDII. As the review in the current TAS states, it is "one of the most musical front ends at any price." I couldn't agree more.

HEGEL HD11 best i ever try.

It is interesting to hear all the positive comments on the PWD but then I have read the Zodiac Gold + Voltikus when combined is slightly better and this is what is driving me crazy. I am always concerned when spending this kind of money that there is a new flavour every month. Is that the problem with dacs; are they just strictly preference and money really doesn't buy you a better dac?

I did a shootout of my original PWD against the Zodiac gold + Volitkus. It was close to a toss up but I would say the Zodiac probably won by a hair. However, I knew the MKII was in the works at the time, so I held out for the upgrade. The MKII took the PWD to a new level, and to my ears it is now materially better than the Zodiac. Throw in the benefits of the bridge option and the ample supply of very affordable used PWDs and the choise is clear (to me).

Synthesis Matrix Dac (tube) Very musical with nice warm sound. Also has USB port and is in your price range.