If you want a good power conditioner, the very best made anywhere was made by Elgar. It is not an audio product, it is commercial/industrial. But it is high power, and can deliver a perfect sine wave at full power (28 amps). It is mechanically noisy, so it has to be installed at your breaker box and then the audio room AC power is then connected to it.
It uses a large isolation transformer, a low distortion sine wave oscillator that is synchronized with the AC line, and a feedback amplifier that is connected to a feedback winding on the transformer.
This is an expensive approach but it works, and other power conditioners are so much junk by comparison. Unfortunately you have to find them used as Elgar does not seem to make them anymore. Some are fairly old (over 20 years) and may have to be rebuilt, but if you want truly clean AC power this is the best way to do it.
It uses a large isolation transformer, a low distortion sine wave oscillator that is synchronized with the AC line, and a feedback amplifier that is connected to a feedback winding on the transformer.
This is an expensive approach but it works, and other power conditioners are so much junk by comparison. Unfortunately you have to find them used as Elgar does not seem to make them anymore. Some are fairly old (over 20 years) and may have to be rebuilt, but if you want truly clean AC power this is the best way to do it.