And to offer what I think I know about an amp's damping factor. It's something that I've generally found has been explained badly, and too technically, but here's my take on it...
When an amp sends current through a speaker system (which is a network of drivers and crossover components), there will be reflections echoed back in the direction of the amplifier. Coils produce back currents, etc. And there are various phase distortions that can be passed back.
That can all intefere with the signal the amp is trying to put out to the speakers, and the more an amp is able to resist such fed-back signals without damaging its output, the cleaner will be its overall output. Damping factor measures the ability of an amp to do that, and the bigger the number the better.