OK I realise this is a diversion, so Jim please feel free to shift these posts elsewhere, but as an experiment I have done this in DSP Studio:
The result is inaudibility of any sound whatsoever over the 35 or so dB background noise in my study from both of my speakers when turned up to 100% and playing any stereo track and a blank screen in the "Analyzer"! This is using my basic PC speakers, but it establishes a baseline.
So as an alternative to the subjective "listening test" (where the same track with different formats is compared
at different times) why not make another routine called say "Play the difference" (or "What's over Red Book?" or something else) in which the user could select any high-res track and have a routine do this:
(it's intended to compare just the left channel of a high res track with itself after being down-converted then up-converted to where it started, but to play back the difference in both channels)
Make a temp file copy of the hi-res track - save that as Temp File A
Downsample Temp File A to 44.1/16 - save that as temp File B
Upsample Temp file B back to the original format and save that as Temp File C
Delete Temp File B
Use Temp files A and C to make a track with the left channel of Temp file A as the left channel and the left channel of Temp File C as the right channel - save that as Temp File D
Delete Temp Files A and C
Play Temp File D doing the following:
Reverse polarity of right channel
Add left to right
Copy right to left (so that any difference will be heard through both speakers)
Imagine the blank looks on people's faces when listening to nothing and seeing nothing in Analyzer, or the smiles on their faces when they can actually hear and see a difference!