I am not an expert, so don't try this at home.
There are some basic things to address:
A. Are you having an issue with your sound that you believe is caused by;
1. Dirty AC
2. Fluctuating voltages, etc.
3. Frequent brownouts, etc.
4. Other
B Once A. is understood, then you can decide if a product will fix or resolve that problem. But more importantly, are you after a certain sound as well which may influence your decision to chose, say, for instance a surge unit w/o conditioning, or a conditioner of the passive or active type?
C. We're all going to pass along our own experiences, but until you try a few, you'll never know what happens to your sound or the (if desired) protection of your equipment.
Units I have had/tried (I'll be the first to throw up some brands for you to look at):
APS 1050 conditioner/battery backup $2500
PS Audio quintet couple of hundred$ish
PS Audio UPC200 same
Brickwall something surge unit buck and a halh
Running Springs Audio Haley $900ish
Audience Adept aR1p wall units $500ish
Audio Magic Stealth Mini Reference $1000
various Alan Maher Power Enhancers $100 to $400ish
Bybee Quantum Chargers $900
