Kevine- I'm using a pair of modded Cary SLM-100s on top, and a modded TransNova 9505 on the bottom. A modded TacT RCS 2.2X does the crossover and room correction duties. By, "correctly" I mean balancing the levels of the top and bottom, as the power capabilities of your amps would be so different. An active crossover(such as a Dahlquist DQ-LP1 or a Tact) is the best way to success in bi-amping. BUT- You CAN experiment with passive bi-amping via your attenuators. You wouldn't need one on the top(tube amps), but just to bring the level of the SS amps down to match that of the mains(providing the Burson unit has a level control). You want to try tubed monoblocks anyway. While you have everything with which to experiment(when you get the tubed amps); why not give it a try? Bet you like it! =8^)