After using a 2000W toroidal balanced isolation transformer designed for recording studios to lower the noise floor of my stereo system, the background was quieter, music were more three dimensional, bass response and high frequencies extended. According to experts advise, the transformer should have higher capacity than the actual power requirement of the entertainment system e.g. 2 to 10 times and much higher capacity is better for the output dynamics and stronger bass. In my opinion, a 2 to 3 kW toroidal balanced isolation transformer should be a good size for most home entertainment systems. In addition, using good power cables between the power conditioner and sound system will further enhanced the audio output.
https://toroid.com/sku/BT2000E/ $891 ea.