I am sure this is going to be up for debate, but that's one thing that makes this interest... interesting. I bought Pat Metheny KIN in 96/24 from HDtracks.com. Here is a specro and chart from the first track.
And here is the same track from my vinyl transcription
My system is as follows:
Benz Micro Ruby 2 -> Linn Ittok LVII / Oracle Delphi mk 2 -> VTA PH15 with crazy high end parts -> dbx 386 ADC -> macbook pro / audacity -> adobe audition noise reduction
It's not ultra amazing but its not a bad system. I go to 96/24 and I wish I could share the results with you. are you allowed to post any short length of a recording for education purposes? If so I can post some of my transcription compared to the HDTracks.
You can see there is "some" information in the HD part of the spectrum. There is more in the vinyl transcription. I think the spectrogram is also picking up the non-linearity of the cartridge, with a dip around 18-20k.
I have my concerns about the HDTracks versions but it looks like there is consistency with energy up to about 28k, so 56k sample rate. I am not sure what to make of it. Other 96/24 tracks that are not mis- advertised, show more like in the vinyl transcription. with more energy well in the HD zone (as it were).
I do have many examples of 96/24 purchases from HDTracks which are not 94/24 based on the same analysis.