I have a Furman P-2400 IT which is their rack mount "pro audio" power conditioner that retails for about $2500. It has worked for the last couple of years and did have to be turned back on a couple of times (it must have shut off due a power surge or brown out). The power in our area used to be quite a bit messier with brown outs during peak air conditioning usage in town. This seems to be less of an issue these days as the voltage readout seems to be fairly constant and I haven't had the unit "pop off" in over a year.
I have like 80 amps of power specifically coming into my equipment closet and all the outlets that lead to TV walls in the house as well as all my home automation crap is connected to this same power main. I did this to try and reduce ground loop issues in our house.
All my equipment in the media room / critical listening area, including the projector is connected either to the 80 amp branch or to my Furman P-2400 IT which is plugged into it.
I tried plugging my amplifier (Pass Labs Class A type amp) and pre-amp in the regular outlet vs. the Furman power conditioner but can't notice any obvious difference. I have 107db sensitivity speakers and which can reveal every hiss or hum in the universe even at the listening position. My Marantz 8801 has a hiss from it that is quite prominent with my particular speakers but the amp had NO audible hum or hiss whatsoever no matter what it was plugged into.
Nelson Pass (Pass Labs) amps are amazing Class A super quiet amps that have minimal circuitry and specifically designed for high sensitivity speakers. No amount of plugging my Crown XLS amps into the power conditioner made any difference in getting rid of the hum or the "veiled" / poor imaging sound they produce.
Basically no amount of power conditioning will make a crappy amp or crappy pre-amp circuit sound "more transparent" or "less hiss". These are characteristics of individual circuits and transistors, etc that can't be corrected with external equipment. I think a lot of us are buying power conditioners to solve problems that we can't solve with power conditioners and then we are justifying the money we spent by "hearing a difference".
Having said all that, I do appreciate power equipment with a few useful features:
1. sequential power on - to prevent a bunch of high power stuff turning on all at once and causing your circuit breaker to trip. Not a problem for everyone... but an issue with my pro-amps for surround sound that don't have soft start circuits.
2. 12 volt trigger circuits - the more the better - to allow a variety of power configurations such as pure stereo or surround sound. I have 12 volt circuits only turn on all my surround amps when I am on a movie input so that they don't produce any hiss the rest of the time.
3. A circuit that will kill ground loops without any other fancy house wiring - which is basically what Furman is claiming it does. Furman generally doesn't make extreme fancy claims but in the pro-audio setups, ground loops are a distinct possibility.
4. voltage regulation for areas with severe poor voltage swings - particularly to protect sensitive equipment. I do prefer that audio gear is built to handle brown outs to some degree however.
Say what you will about PS Audio stuff but they do give you a consistent current and voltage. If you have regenerated power, the problems such as ground loops should be eliminated with anything plugged into that device. Their new products do have a lot of options for automation that just about nobody else has that I have seen on the market. Do I want to turn off my power strip from my cellphone app tho? (no.... wtf). I don't think there is anything inherently wrong with PS Audio stuff, just that there is no reason to believe the claims of miracles. Most placebo / snake oil vendors on radio and television offer the "money back guarantee" or the "free trial" so you can notice a "difference". Their products are usually 1000% markup so they can eat the cost of the "free trial" because they only need to sell a few to make a profit with long term customers. PS Audio current conditioners look reasonable and well built and I would gladly pay less than $1000 bucks for them because they look functional and have capabilities that might help me. Paying $5000 retail... I'm pretty sure that would be insane and would be better spent trading in/upgrading my speakers.