Art Blakey's Jazz Messengers with Thelonious Monk (Atlantic.4 Men with Beards)
I listened once and then compared the 4 Men with Beards LP to the Rhino CD. (I should know better by now than to drive myself crazy doing this sort of thing.) The CD version jacks up the sound and gives more presence to the bass. The LP sounds more relaxed, but the bass is recessed - perhaps that's how the bass sounded in the original issue. In the end, I'll keep both - the CD primarily for the additional tracks.
Note to myself - listen for enjoyment - not to make comparisons.