PA-100 Power Attenuator : I own 2 of these. They're okay.

I have two of these, and I'm currently using them in two different set-ups. The first is through my Marshall DSL40, between the 'head' and the Creamback I installed. It definitely works, and lets me push the amp, but keep it quiet. BUT...for some reason when I'm using it, the Marshall 6-switch footswitch acts up and sometimes loses power for a moment. Fine for at home, but I'd never want that to happen at a show.

My other one is set up between a Peavey VK100 and a cabinet with two V30's. Again, this allows me to drive the head, but keep it at a reasonable volume for practice. No issues here, but you can definitely hear the attenuator's fan working overtime on this amp. I was surprised that I could hear it.