interesting.
as i recall (and Jazdoc can correct me if my memory is wrong); a few months back Jazdoc brought over a very nice OP 6-eye mono of Jazz Party in Stereo and we compared 'Malitoba Spank' to the 45rpm Classic reissue and we both preferred the 45 reissue pretty much top to bottom. the mono was very very good, just that the 45 was better.
this was with the Talea 2/Miyajima Premium Be Mono for the mono, and the Telos/Ortofon Anna for stereo both played thru the darTZeel preamp internal phono stages.
in a few weeks i'll have a second Telos for the mono (and maybe the Miyajima Zero mono) and i guess we could try it again. i would not anticipate the arm making enough difference to close the gap.
added note; as i sit here thinking about it; it's possible that the OP was a stereo pressing, and not the mono. now i'm confused.
Jazdoc??? what did we do?