VANDERSTEEN 3 A SPEAKERS

If the designer advises against it it probably is not a great idea.

I used the 3A Signatures a few years back with a pair of stereo Theta Dreadnaught I's. I used one amp for each side, left and right with 1 channel driving the upper section and the other channel driving the lower. After evaluating the sound over several weeks, I came to the conclusion that the sound was not as good as using a single Dreadnaught for both channels. For whatever reason, the sound seemed to become a little disjointed like the blend between the upper and lower sections was not right.
Changing back to a single amp brought everything back into focus and the speakers sounded better-actually, noticeably better. That ended my biamping. Biwiring is a must though. It is better.
I have heard that with these speakers, an oscillation can occur because of the characteristics of the crossovers with a biamp. Richard now recommends against biamping because of this possibility. I don't really know if that was in play with my system but for whatever reason it just didn't work out. So I sold the other amp.

Biamping is not a good idea with Vandersteen speakers, especially with solid state amplifiers which can become unstable due to the capacitive load of the mid/tweeter crossover.

What is recommended and is superior to biamping is adding two 2Wq powered subwoofers to take over the deep bass. This is going to add 300 watts per channel of power where it is needed most and simultaneously free the 3A Sigs from a tremendous burden in the low frequencies.

I am a Vandersteen dealer.

I wouldn't doubt Richard's advice regarding his speakers.