Enough noise reduction?

I highly doubt that Stereophile and ASR are using lab power supplies for their measurements.

@yage and you would be wrong.
(Not for amps, but for the front end gear tests… I believe that you are right for amp testing.)

If I did not attract a 2 weekban there I could look it up, but it is mentioned a some of the videos.

This thread had made me realize that a measurement not usually taken or published is power supply noise reduction ratio.

We get the S/N+THD specs, and these assume ideal AC power.  We also should see something like how well AC noise can make it to the audio outputs.  Not an impossible test.

Yeah @erik_squires Probably a test for both for a voltage field, and for a current field would be good.

@holmz 

I'm still doubtful a lab power supply is used. It just doesn't make any sense. A lab 'bench' power supply provides DC, not AC. Also, these components are consumer products meant to operate off of standard household power. If you want to measure and test them, wouldn't you want to know the performance given wall power?

Anyway, I've done an online search which didn't uncover anything definitive. I sent an email off to Stereophile. I'll post an update if I get a response.

@holmz 

I'm still doubtful a lab power supply is used. It just doesn't make any sense. A lab 'bench' power supply provides DC, not AC. Also, these components are consumer products meant to operate off of standard household power. If you want to measure and test them, wouldn't you want to know the performance given wall power?

No, I don’t think so.
One would want just the noise and distortion from only the unit.

But many would also want to know how the unit operates with dodgy power.

Since we do not know what different cities, countries, and individual houses power looks like, then the easiest is just use pure sine wave power.

Do it right and install an isolation transformer. That protects your system, improves the sound, and takes power cables out of the equation. I've done the tests and I have three isolation transformers in the utility room, 'cause they tend to hum when they're working hard.

Sort of like Jiminy cricket, they whistle when they work? @terry9