I still can't comment on the UR7 versus the UR6's, but I did have the opporunity to compare them with some Acoustic Zen Matrix Reference II and its no suprise that the UR7s came out on top for me. I'm pressed for time with law school finals begining tomorrow (monday) so I won't do a lengthy write up, but some of my impressions are as followed.
Tonally the UR7s definitely come out on top for me. The Matrix References are the warmer of the two cables, but sound somewhat artificial in comparision and, though it can be pleasant if your in the right mood, it can get a bit syrupy and annoying.
Resolution wise the AZ's sounded better then I recalled (used to own them, now I'm just borrowing) but the UR7s still bested them. Both cables were great at revealing small details of a performance, but the UR7s just seemed to really pick up on some of the really small nuances of a piece which added to the realism of the playback.
Imaging wise I would say that both cables were very accurate. On the soundstages they reproduced both did a great job of laying everything out to the point that you could really close your eyes and hone in on where each instrument/peformer was located before you.
Soundstage wise, the UR7 definitely got the nod in my opinion. The both had similar width and height, but it was no contest when it came to sound stage depth. As a result the UR7 presented imo a much more layered and exciting sound. (even my non-audiophile girlfriend was able to pick up on this).
Overall for me, the UR7 is just the superior cable. Its hard to break any piece of equipment down into its performance in various categories and still convey the essence of what it is. Many pieces of equipment do a lot of things right, yet just don't do it for me--in the case of the UR7s, there is a certain rightness to it that is hard to describe but very pleasant to expereince.
I can confidently say that any fan of the grover sound will like his latest revisions and will also add that those unfamiliar with the sound and in the market for a new inteconect, should check these out no matter how big their budget is.