well my .02
i don't know much at all about power and high end audio...
but i own an isp, i have a roo m full of equipment that costs far more than just about any stereo rig you can dream up.
in my experience people worry so much about voltage spikes but never seem to think for a minute about voltage drops.
i have seen a LOT more voltage drops than spikes.
i rely on ups' - that stands for uninteruptible power supply...
there is a huge difference between ups's, i bought one brand originally and was happy with it and then came upon another brand that cost a little bit more but seemed better.
i moved to a different building where there was electrical interference and the one brand that was a little bit cheaper didn't stop the interference, but the other brand did.
so anyway, i ONLY use APC brand ups' www.apcc.com
i am not related to the company in any way etc. etc.
but i would start with a UPS. I have APC ups' on my home theater as well as all computer stuff at the home and of course the office.
people spend a fortune on these power cables, the power cable can't condition the power coming out of the wall!