Imo if you are going to use anykind of stabilizer ( automatic, servo), UPS, CVT etc, for an audio amplifier, then it becomes high impedance power supply for the amplifier. Yes your amplifier could be protected from over / under voltage, but the SQ would be affected to a great extent. Because of this reason, I plug directly to wall outlet, no power conditioner or power regeneration etc. Even a humble line filter is a strict no for me as they rob the power lines of the harmonics content which is so important to play music.