To clarify my previous post (I figured I would get some disagreement--but that's okay--I don't feel there really are any absolutes in audio (except don't run your Class A amplifier in a full bathtub). Anyway, I do own Martin Logan's, they are monoliths. I have friends that own Requests and SL3s. We all love the Martin Logan. My current set-up is ML monoliths with Levinson 20.0 on top and Krell KMA 160 on bottom. I have run mine on tube amps. It didn't work--not at all. Now in fairness--the panels of the monoliths are very difficult to drive--more so than the SL-3, and I wasn't using a megabuck high powered tube amp either. I have listened to Requests driven with very expensive tube amps--they sounded great!! I do love the sound of tubes with the panels if the tube amp is powerful enough to handle it. When we did this the bottom end did lose a bit of dynamics in the bass, but it was worth it to hear the panels with the tubes. As to the SL3--I have not heard tubes on the SL3--but I have heard it with Levinson 27, which also sounds fantastic--it is not bright at all (Krell probably would be, but series 20 Levinson is not bright at all). While I disagree with Bigcigarman's point about Levinson and Krell, I am intrigued by the Sonic Frontiers with SL3. Have you listened to this combination? If so this might be a very good recommendation.