When you strip away the marketing hype from Paul at PS Audio and live with their regenerators, I have owned the P20 for 2 years, and before that the P5, and before that the PPP, you realize they:
- produce line noise - the regeneration is not silent, or “free” - it does add some noise
- they are also susceptible to incoming AC noise. That’s why the power cord feeding the P20 maters. At times, there is more background noise in my system, which shouldn’t be the case if the output is “pure, clean” AC. The truth is that it is still starting with (dirty) AC, and some of that does come into the output
- a pure sine wave is not a requirement for equipment. It seems to make sense that a nice sine wave is important. But it’s not. Your equipment runs on DC and could care less about the incoming sine wave, as it’s flattening it anyway.
- they do nothing to filter noise being generated by your equipment, that gets put back into the line, and therefore affects other equipment
Don’t get me wrong, the PS Audio Regenerators do work, but they are not perfect. As was said a few times above, you have to listen and trust your ears. A PS Audio may be best for you, or a Shunyata Denali/Everest. These are the two leading contenders today. Audioquest has been surpassed by the latest advancements from Shunyata.