A little late to the dance on this one, but my 2 cents. I am in agreement with Nsgarch, somewhat. The difference from what Nsgarch said, I plug my amps into a simple filter. It is a non current limiting filter, I feel I get some benefit from the filter at a very small cost.
As far as an active power conditioner, I used PS Audio's P600 for my Audio system several years ago. I had a Cary V12 power amp at the time. When plugging the amp into the 600 and using any of the Multi-wave setting, I would get mechanical hum from the output transformers on the V12. This did not occur when using a straight sine wave setting. After talking to Denice from Cary, and, reading all I could at the time, this is not an uncommon phenomenon. Denice said as well as PS Audio's web site, this did not hurt the amp in anyway, but I decided not to run the amp through the P600 anyway. It was caused from the metal laminates vibrating on the transformers. The P600 now was used only for the front end of the system, a little over-kill, a P300 would have worked just fine for this application, I sold the 600 and bought a 300 and used this setup for 4+ years. About 2 years ago a friend of mine started reading about these passive balanced power conditioners. He bought a Blue Circle MR800 and brought it over for a listen. It was as good as the P300 but without the heat and power usage. I sold the P300 and bought the Blue Circle MR1200 thinking I could now use it for the Power amp as well as the front end. This worked great until now when I decided to actively bi-amp. I guess my point is as far as the amp goes, buy a simple non current limiting filter, I am using the Welbourn filter, cost $150.00 6 months ago. You do have to assemble it but is kind of fun and cost effective. The PS Audio's Ultimate Outlet would also work very well, a lot more money new and a little more money used. The good news about buying this piece used, these devises don't have anything that could be worn over time.
As Nsgarch says, a good passive balanced power conditioner (I might ad Blue Circle's name to his short list of passive conditions), the difference from his point of view, use it for the whole system front end and the amp, just make sure that your wattage used is not more than the power conditioners rated output by quite a bit. You need to allow for added short term power from your amp, a whole other issue. Or, a balanced power conditioner for the front end and a filter for the amps. As I stated earlier, this is just a 2 cent opinion and only a 2 cent opinion.
Oh, don't forget to use good power cords, this maybe is the best performance improvement regarding power supply...........Bob