Hi Sidvee,
I have not heard the Playback Designs, but have heard a lot about it.
Among all the digital sources I have heard the best (in musical terms) are these:
1. TAD D-600 (undoubtedly the best)
2. Combak Reimyo CDT-777 + DAP 999EX (heard it only as a combo, outstanding!!)
3. Naim NDS
4. Audio Note DAC5 Signature
I have not heard the top line of Esoteric (P01/D01), Zanden, Einstein and some more. However having heard most of the other usual suspects (EMM Labs, AMR, ARC, Burmester, Esoteric K01 and the likes), the ones I have listed are absolute stand outs. They make music and they do it in a way where one feels lost within the musical experience. Some of these are very expensive while some are affordable but all of them belong to a class which is normally away from the usual suspects and most magazines never talk about these products, simply because if this is brought in the discussion all other products being reviewed in the article would have to be denigrated.