New? thoughts on driving MBL 101s with tube amps

Gregm, thanks for the help. I've actually never bi-amped before so I'm a total rookie here. I can clearly see the advantage of actively bi-amping with an electronic crossover but I no longer believe that there is much to be gained by passively bi-amping (using only the passive crossover in the speaker). In this configuration, if I understand correctly, attaching a tube amp to the high/mid section and a big amp to the woofer section will not take any stress off the tube amp since it is still trying to amplify the entire frequency range.

Yes, it's difficult, but ASAIK the phase is relatively benign and all you need is some extra energy -- but not that much extra energy. So a tube would do the job -- since you're looking into a small tube.

I'm told that the mid-high section of the 101 (with the big aluminum football) is just as difficult to drive as the 12" woofer on the bottom.

Big amp for bass, small amp for mid-high. Should be good. Especially so, if you cross-over at line level rather than speaker level. I think MBL once had a client who wanted to x-over passively at line level... but can't find the reference.