Hybrid amps may be another safe bet. I'm using a pair of Blue Circle BC2s (hybrid - 75wpc Class A, with one 6SN7 tube per amp) to drive my Audio Physic Virgos, and they seem to do a wonderful job. I believe the CEO of Blue Circle uses the same amps to drive a pair of Martin Logans (can't remember the model) that are notoriously difficult to drive.
Cheers,
John.