1) beware of 'DR' readings from LPs
2) yes, 'high rez' releases have been unpredictably compressed and/or bandwidth-limited (i.e., not the 'audiophile' quality claimed) ever since they were first touted. Here's a
thread I start about dynamic range compression in DVD-Audio releases, way back in 2008 (discussing some older DVD-As).
Stereophile also ran an 'expose' on this , some years back.
It's been a scam from day 1. HDTracks isn't 100% fault, since they only sell whatever files the record companies give them. They don't do their own transfers. They *should* check their files though. They *should* make it clear that the format is not the sound. Sticking a Redbook master in a 96/24 container doesn't make it 'high resolution'.
3) if we're gonna do this, we should agree on what FFT settings to use. Audition offers a number of FFT size and window options, for example.