Mike,
I can tell you the Lamm's bass is where it separates itself from the MXR. I tired them both on Kharma Midi and also on 5A with the same results. The power was about the exact same on both amps even though they are rated much different. One is class A and the other is not. As all Lamm owners know don't let the power rating fool you. They have current and control which is much more important.
I don't own either of the two amps anymore for the record. I have found better amps then both for my system. I also had the ARC Ref210 that sounded better then both and had better bass.
BTW the big misconception with the 5A is that is doesn't matter what amp you use for the bass because it has a built in powered woofers. That is 100% wrong. It uses an active crossover so it acts differently then if you were to use a Sub woofer. Every amp I put on the 5A changed the bass 100% and it is not a small change either. With some amps I have the bass setting is flat and other I have as much as -3db down. 5A owners know what I'm talking about. People think they can just put an amp that has very little bass and they are not hearing what the speakers can really do. With the Lamm's I got flat bass in my room to 18hz with the MXR I got it flat to 24hz. Nothing different other then the amps. Plus the bass was tighter and much more defined with the Lamm.
For your 20T I think you need more power then either the Lamm or MXR can provide. Aerial will tell you that. The 20T love love current. I would love to hear the Krell EVO on them or a big Boulder. I think the 20T would be world beaters.
