One does not normally start with a conclusion, they start with a premise, "The audible effects caused by RF noise are difficult to objectively measure yet are simultaneously subtle and obvious. Suffice it to say that they manifest as a reduction in musical transparency and increasedlistening fatigue. "
Curious how you were able to listen to headphones/speakers which would transmit RF back to your DAC (you claim direct connection, no amplifier).
In your white paper, you use a log-periodic antenna rated for 1Ghz-18Ghz (or 1Ghz -2Ghz model dependent). That will be great to cover intentional radiators, but most RF energy from unintentional sources is well below that. Testing below 1GHz would be far more useful in most environments. Curiously you show results down to 100KHz for which your antenna would be poor. What you identify as standard radio communications and microwave radio communications in your "Rural Isolation Ambient Zero Baseline" are predominantly VHF and UHF television (UHF = 470-806). (p.s. Your sweep times are way too short for high quality measurements).
Of course, shielding the outside of the DAC doesn't negate likely the largest unintentional RF components (by intensity), namely components inside the DAC. Of course, most DACs do seem to have metal cases which are effectively Faraday cages, so sensitive circuitry with the exception of cable entry would be covered.
W.R.T. claims of "Sounds Better", there is no discussion of the test protocol, the number of testers, etc. so I guess we just "trust you"? A future test is identified as "Double blind listening tests with a variety of subjects/music" I would think proving a problem exists would be the first thing to do?
