So far I brought in a few clips from an old JJ Kale (surprisingly low levels), Eric Clapton's Pilgrim (lots of dynamics but clipped a bit), John Mayer (same).
Some tracks were quite compressed according to the wave forms.
It varied a lot.
I normally use my monitors and sound card thru my mixer for playback anyway so the levels are identical to the CD. Nice for comparisons.
I assumed the old JJ Cale was pre-loudness wars.
A very interesting exercise.
I'm interested in lots of genres so I'll need to make a set for each genre.
(Jazz, several kinds of blues, soul, older rock, southern rock, reggae, folk, Latin)