I had incredible success driving a pair with a Theta Dreadnaught 1 vertically biamped. It’ll be hard to find the pig-tailed cabling to do this now. I don’t think you can go wrong with Ayre, Theta Dreadnaught (First gen only), Quicksilver, McCormack etc.
I currently drive my 5A’s with a pair of Theta Citadel 1.5’s and love them.
I currently drive my 5A’s with a pair of Theta Citadel 1.5’s and love them.