Hi - I own Vandy 3A Sig's, and am using a 4B-ST as the main power amp. As I understand it, the new "250" is simply half of a 4B-ST. I am very pleased with the 4B-ST driving the Vandy's, but I have not heard the "250" yet. Given that the "250" is derived from the 4B-ST, there is no reason to think that the "250" shouldn't work fine with the 3A Sig's. However, an audition -- in your home -- is still advisable.