Power Conditioners

I m not convinced about active power conditioners in front of power amps, nor of low voltage devices, for that matter. All have an impact on the sound, not always for the better, either because of shifts in phase, compression or emphasis of parts of the frequency spectrum. In my experience the best results can be obtained by installing a separate spur all the way to the mains box and then employing passive filters. Highly recommended: Acoustic Revive RTP-4. My power amp is a Wavac EC300B and short of $30,000 Wavac power conditioning I have found nothing that comes even close.

They are not snake oil. I had a very slight (but audible) buzz/hum with nothing playing and the volume at a normal level. Put in a Furman 15 and the noise vanished. I don't know what they are talking about with extra wall warts. You plug the Furman in to the wall and everything else you want into it. It even has different outlets for amps, low current, and video. Peace of mind and less noise. And for less than $1K - even less if used.

I was wondering if there are power conditioners that can solve the spikes you hear over the speakers when you switch on or off the lights?

Never have had that problem with or without a conditioner. Only way you'll know is trying one in your environment