Which Krell for driving subs?

I now have Krell monos for the main panel of my Audio Artistry Beethoven Speakers. For the subs (operats in 20 to100Hz) with 4 12iches in each cabinet I need at Krell stereoamp. I can spend 3500usd on this amp.Which amp should I choose?
I agree recommending Crown. Take the Crown K2. It has no fan, is absolutely fantastic for bass amplification. I use it in bridged mode for my Wilson Audio WHOW subwoofer. For Krell you surely pay much more but you may get less.
I must agree with the above posters. I tried both Krell and Bryston before I settled on a QSC M3000. The QSC just sounded better...more slam and more tonally correct. It DID have a fan, but I was able to hide it away in a ventilated cabinet.
Ulf, I own the Audio Artistry Beethoven Grands and use a Krell FBC200 amp to drive the woofers. The subs sound awesome. Other choices may be either a Plinius SA100MKIII or an Aragon 8008BB, also designed by Dan D of Krell. The subs in your speakers are fairly easy to drive; its the 10" midbass woofers that soak up all of the power. For a seamless match between the bass and midbass, I would go with another Krell amp for the subs.