I've owned 2A Sigs and 3A Sigs. I've had very good luck with McCormack Amps with the SMc mods. My favorite amp for Vandys in MY system was a Belles 150A Reference. However, when I purchased the 3A Signatures, the owner was powering them with a Pass Labs amp (don't know which one) and it was the best I've ever heard Vandersteens sound.
Good luck in your search.
Good luck in your search.