Having owned both, I think the Ref7.1 is just as good as the PWD MK2. They're very different, but I didn't come away thinking one is better than the other.
Ref7.1 = more bass, bigger soundstage, more neutral sound
PWD MK2 = more prominent and liquid mids, more microdetail, sound signature geared towards being musical rather than neutral (ie. warm, smooth and forgiving). The PWD was also more holographic in its imaging/layering, not that the R7.1 was bad. Only thing was, it played in a much smaller space than the R7.1
In the end, I found the Ref7.1 a bit more enjoyable overall to listen to because of the bass weight mainly. For some mic-centric genres, the PWD was more enjoyable. It really depended on the type of music.
I feel it's important to point out that while the PWD had more microdetail, the Ref7.1 didn't seem lacking, nor did the extra detail add to the enjoyment (for me). This was surprising to me because I'm a detail guy...I guess it was just the way these DACs present that detail.
(Comparison was done with the MK3 JKSPDIF > Ref7.1 / PWD MK2). I didn't include the Off-Ramp 5 (with all upgrades) or USB inputs because that would just complicate things. With the OR5, both DACs were superb, but the Ref7.1 improved more and became the better DAC IMO. Also, the USB input of the PWD was almost as good as the MK3 JKSPDIF feeding it, which was a step down from the OR5.
