Magnepan 20.7's & Tube Amp

Depends on the size of the room, type of music, and how loud you listen to your music. That said, the closest experience I have is driving 3.7 model with Cary SLM-100 @ 100wpc, in an average size room and I felt the speakers were starving for current at medium to high volumes. 

which one has more amps into 4 ohms?

which one has more amps into 4 ohms?

This is a bit of a trick question.

The amount of current will depend entirely on how much power the amp makes into 4 ohms. If 200 watts, the current will be 7.07 amps regardless of the amplifier involved, tube or solid state.

Wendell Diller always made a point of telling me that the best he every heard that speaker was at Johnathan Valin's house using a set of our MA-2s. What we found with Maggies in general is that if you want to play the speaker with tubes, keep the speaker cables between the amp and speaker really short- over a foot is too long! Place the amp with the speaker terminals facing the speaker's terminals and install the really short speaker cables.

This is a really good place to have monoblocks :)

Anyway, this gets you the best bass. Don't worry about vibration from the speaker; the amp will see very little. Maggie owners know what I'm talking about.