Putting a high impedance probe on the DC BIAS point feeding the X-isitors isn’t theoretical, but the issue of can we hear that is there.
The real issue is no one wants to be the manufacturer who “proves” their equipment isn’t improved with better AC power as this can be rubbing other vendors the wrong way. But…the DC bias voltage aren’t impossible to monitor real time, so no theory there on seeing what the sinewave does with no RF, and injected RF of some sort.
The FUD is; will the injected RF EVER be there if you don’t artificially put it there until something happens? And, RF is a pretty broad definition of a “problem”, too.
So just thinking out load. We have a “bias” on solving this one!
Another thought, many CLASS D amplifiers have as much as 0.200 milli-volts ultrasonic, not RF, noise @ about 200KHz and up or more at the SPEAKER TERMINALS! This is actually LOWER than what we call RF (1 MHz and higher) and well closer to the audio pass band.
If this amount of RF is standard, or very near standard, practice for many CLASS D amps, how can they get pretty good listening responses by reviewers? Is this RF a problem? Is air born RF any where near this magnitude (no), or as low a frequency (no).
I’m trying to define WHERE we accept above audio passband (20 KHz) noise and perceive it as OK. Class D amplifiers are a case study for AC regenerator noise “problems”.
A happy belated 2023, everyone! Posting the following URL, on the subject of audiophile grounding boxes, to awaken this thread from its deep 2.5 year slumber. It’s relevant to the topic of noise/RFI, and a huge myth-busting eye-opener to those who believe in “grounding” source components!