Thanks, gents. Is it correct to say that there are different DEGREES of mismatch which might manifest differently? What I am hearing is low frequency rumble/distortion that is inaudible unless the volume is cranked up. Interestingly, the rumble/distortion exists during quiet/silent passages so this does not appear to be external vibrations from high SPLs disturbing the table, which is well isolated. I checked and the cartridge setup appears correct (overhang, VTF, etc) so it does not appear related to this either. Could there be a slight mismatch that is only audible when the volume control is aggressively amplifying the tonearm resonance? This is a buddies set up (Systemdeck II with a Rega arm and Goldring Eroica) which SHOULD be an OK match. Unfortunately, he lives quite a ways from me so I'm not able to do a lot of listening and intervention but thought I would get some opinions in an effort to help him out.