The past few months, I grappled with an intermittent loud pop issue in my office 2ch setup (new 2nd system). The pops were singular, but LOUD. Startlingly so. Even louder than the peak music levels. I went through all the usual suspects -- record cleanliness, static discharge, phono stage overload margins (tried 5 different phono stages). Nothing helped. Turned out it was AMP clipping, caused by severe low frequency feedback.
The KAB rumble filter stopped it (an easy solution), but I went ahead and really fixed the issue with proper turntable isolation -- which was not easy, mind you.
I’m not sure that’s what you’re grappling with here, but thought I’d mention it because this almost drove me insane. Does you incidence of pops always correspond with musical peaks / crescendos? That’s probably amp clipping. At first I was SURE it had to be static discharge, but then I started to notice the POPs were more likely to happen at the same point of certain tracks (where it was loud and especially bass-heavy), and only when the volume was high. A good example is the opening of Elvis Costello’s "(What’s So Funny ’Bout) Peace, Love, and Understanding" track on "Armed Forces", and Foo Fighters "There Is Nothing Left to Lose" (at many points on this album lol).
It seems unlikely a change in cartridge and could cause amp clipping, but it’s possible the new cart could have a generally stronger LF response (or even a peak in the wrong area), or exhibits a different resonant frequency with your tonearm, or even encourages you to use the system at a slightly higher volume than before.