I upgraded my 3A's to the Signature version last summer, and was very glad I did. Ditto most of the comments above: cleaner, more transparent highs, and better balanced overall. I think both the 3A's and 3A Sig's clearly benefit from a larger power amp. I am using a Bryston 4B-ST, and it's turned out to be a great choice for the 3A Sig's. The 4B-ST is rated at 250 wpc, but actually puts out about 290 wpc. If you need less juice, you ought to consider the Bryston 3B-ST, which puts out about 150 wpc. The 4B-ST also does a terrific job of handling the bass, which really improves the bottom end of the 3A series.
Upgrade Vandy 3A's or get larger amp?
I'm driving a pair of Vandersteen 3A's with 65wpc; far below the recommended power of 100 wpc or more. They sound fantastic even with this limited power, but I know I can do much better. I'd appreciate hearing from those who have upgraded their 3A's to 3A Signatures. Is it a substantial difference in performance for the $850, or would I be better putting the money towards a larger amplifier?