AudioQuest’s Niagara 1000 power strip

[David A]

…But for me the bigger question is, am I willing to continue to ignore what is the most fundamental critique on power conditioners which is "once it enters the amp and is converted to DC/ passed on to the capacitors from which the amp is then actually powered, all those things become irrelevant"? Devialet about the Expert power supply: "Power supply is unaffected by the mains and runs silently with remarkably low electromagnetic disturbance. .. Driven by a microprocessor, power supply is automatically protected from anomalies including surges, clips and overloads." …

All I can say is that I found the Isotek Aquarius I was running when I got my Devialet did make an improvement and that replacing it with my PS Audio P12 made another improvement but not in the bass. I couldn't use the Shunyata power cord I was running to the Aquarius with the P12 (wrong IEC plug) so I started by using the stock cord that came with it but replacing that cord with a Shunyata Alpha really made a difference to the bass compared to the stock cord.

As for Devialet's comment which you quoted: low electromagnetic disturbance is good  but that sounds like they're referring to the Devialet not producing electromagnetic disturbance, not to it being insensitive to electromagnetic disturbance from elsewhere. Being protected from surges, clips and overloads sounds like voltage regulation. Neither sounds like they are referring to reduction of noise on the power line which is one of the main reasons for using a power conditioner. I'm not suggesting that they're wrong in what they're saying, both of those statements point to the power supply in the Devialet being of good quality, but they don't point to a claim that it will not benefit from a good power conditioner. In my experience it does benefit from one but my experience is with the power in my area and with the other components in my system. As I said, these things vary from user to user.

Yes, there are people who say that power conditioners can't make a difference because the power supply in your components should fix all problems with incoming power. In my view anyone who believes that power conditioners shouldn't make a difference because each component's power supply should be doing that job properly should also believe that each component does the job it's intended to do properly in which case there should be no differences in sound quality between products of the same type. We all know that isn't the case and that there are differences in sound quality amongst products of the same type. I see no reason to assume that all of the things which make a difference to the sound quality of different products of the same type are located after the power supply and that there are no differences in the quality of component power supplies which affect sound quality.