As one who is very familiar with the Vandersteen's and a former owner of the Audio Research SP-9 Mk III, a very high priority of mine would be to sell the SP-9. You will never get the best from the Vandersteens with that preamp. I don't know your budget but top of the line alternatives include CAT, Hovland, Ayre, Aesthetix. A good budget alternative would be Audible Illusions (Modulus 3 is better than 3A). As far as amps go, I have heard the 3A Signatures with Belles (not impressed), Bel Canto (not impressed), Ayre V1 (very good, but not fantastic) and Rogue Audio (not enough bass). Have heard the 3A's with Krell, Plinius SA-100 and Pass Aleph 4. I would match the 3A Signatures with the Alephs. The Aleph should be available for about $3000. They are warm, smooth, have great soundstage and detail, with terrific bottom end extension and very good top end extension. The Vandersteen's are so dynamic that they really don't need an explosive amplifier like the Plinius or the old Krell amps. The 3a Signatures I find to be less dynamic than the 3A's with a slightly improved top end over the 3A's, so I think it would be a very good match with the Aleph's which are a little laid back in the high end. If that is still not enough slam or high end detail, consider a Pass X-250, but in my opinion, it shouldn't be necessary since the Vandy's move a lot of air on their own. These amps will take your system far beyond the McCormack amps' capabilities. But, if I were you, I would work on the preamp first. If you a/b the SP-9 with any of my preamp suggestions you will never go back.
