You've beat me to this one as I meant to bring this topic up myself. The topic of high end expensive sound systems came up the other night and a buddy mentioned that some people use mains purifiers for their systems. Apparently it does even out the fluctuations of the mains power supply, producing a better sound.
Never heard of it being used for the kind of bass amps we use, but I did wonder if it would be worth trying out.
I did read on another thread that someone protected their rig with an RCD and surge protected four way blocks, but that's a bit off the op's topic really.
Watching with interest
T