If you have a 300B amp, you should have enough power and damping for any of these speakers. I think the issue comes up more with the lower- powered 45's, 2A3, and some other single-end designs like the Zen amps, which have outputs of 2-4 watts. The extra few watts you get with the 300B should make you fine. The topology of the amp may assist some too, if it's parallel feed output.