Good guitarist. Tight rhythm and sense of the line. Hey, lately we're getting more nylon string stuff.

I think the EQ balance is OK, maybe a little shy in the lower mids, but there's something else about the sound - kind of like a mic, room or processing related hard edge to it. Hard to know what's really happening here with the sound... I'd be interested to hear the orig unprocessed wav file. Also be interested to know the mic's used, their distance and configuration, pre's, room dimensions including ht. As it is, I think things are being brought out in it (squeaks, high freq buzzes, nail noise) that could be minimized with various different approaches.
In recording the duo, are you planning to do it as a "live" duet or by multitracking?
Tim