Bi-amping is the way to go. The easiest way is if your preamp has two sets of pre-outs, and use one amp for each speaker. I would stay away from tube amps altogether for that speaker, but that is my prejudiced opinion. People that like tubes like distortion. Remember to keep the length of all interconnects the same to the amps to keep the gain the same. Also remember that one great amp will out perform two lesser amps used for bi-amping. If you want to get complicated, you could do something along the lines that Jrawwas above suggests, but he's making it sound a little too easy. And why add more to the chain than is necessary? If budget is no problem, I'd just get the most powerful Krell or Levinson I could and bi-wire. Good luck, and happy listening!
