IMHO I think you will enjoy the LCD-2 with any amp you pick. Someone said before in this thread that the LCD-2 is already a highly colored headphone, I agree 100%. I have not heard the LCD-2s sound bad on any amp that I've heard so far.
As far as the Peak/Volcano sounding superior to a 4-channel β22 - this would be high debatable. In my search for amps I was told my many of people which seems to like the kind of sound that I do. That the Peak sounds thin and shrell at times compared to the β22 and that the Peak just don't have the muscle to produce the type of bass impact and response that the β22 does. It's all subjective anyway. Lets just say I'm really glad I picked the 4-channel β22 from YBM.
For a tube amp I have on my radar the LF and ECBA. However, their price is crazy.