HiRes has been one of my bugbears for years.
Firstly, anything originally recorded on analogue tape with a S/N ratio of (at best) 70dB and a frequency response that's 3dB down at 20kHz as most studio machines are, can't be HiRes, however it's digitised.
Secondly, anything recorded with high quality large-diaphragm condenser microphones like Neumann or AKG won't have a frequency response much exceeding 18kHz, so won't be HiRes, whatever the sample rate.
Thirdly, even with a recent all-digital recording, using a wideband microphone or Direct Injection, exactly what signals of musical significance are there above 20kHz and below -90dB? Certainly there's the high frequency whistle from any SMPSs, wallwarts and the like, ditto with computer screens. There's fan noise from any computers and aircon, and there's traffic or aircraft rumble, there are also the musicians breathing, shuffling their feet, turning over pages of the score, but how are these musically significant?
To me, HiRes is a con, perpetrated on the music buying public to prop up the recording industry and/or to get more money out of the back catalogue. Just how many copies of DSOTM does anyone need?
There are good technical reasons for recording at 24 bit or higher and 96k sampling or higher, as the files are going to be processed and edited but none whatsoever for releasing a finished recording that way, except to con people into thinking they're better and so pay more.
S.