I drive my Platinum iv's with an Adcom 5800, directly driven by Wadia 6 CD player. Plenty of power for a large room. The Adcom has a damping factor over 1000, which I consider helpful with those 8 12" woofers! I also can biamp using Carver's modification kit. In this case, I let the Adcom drive the woofers of both speakers and use a Classe Audio 25 to drive the ribbons. The Wadia has double output so one amp is fed from bal output and the other from unbal.
This connection works fine but it's less efficient overall, and you have to reduce the gain of the more efficient Adcom.
Hope this, late as it is, helps. Jim in Asheville