When my roughly 8 years old AlenGeere WattKiller 100 stopped working I needed a new attenuator for my Deluxe Reverb. Reviews were good as well as the price for such unit. So, I ordered one. Since I didn't have the chance the compare with my old unit. I couldn't be sure about the sound quality at first. But now I am sure that it adds a considerable amount of distortion to the amp's output through the loudspeaker. The sound is much cleaner when I remove the attenuator between the amp-out and loudspeaker. For a high gain amp, this might be a issue that one can ignore, but not with a clean amp. Thus if you consider this product for a clean amp, I wouldn't recommend it. If I wouldn't have missed the return period, I would definitely return it and look for alternatives.
In my opinion the unit lacks of a very important feature though it is very interesting one with 3 output options and 2 control knobs for speaker output and line-out: Bypass switch! It would even make it okay to keep the unit for me! I could activate it when I need amp overdrive and bypass it when I play clean in lower volume levels. Sadly, it doesn't have such feature...
Now I am looking into repairing my old attenuator and trying to find a buyer for this one. :(