Cartridge upgrade for vintage TT - MM or MC?

I’m not familiar with the pearl cartridge but if it sounds dull, try to raise the vertical tracking angle a little (no more than 1/16 of an inch) to see if it adds any sparkle. Generally if a cartridge sounds dull & muddy, the VTA is set to low. Again, I’m not familiar with the pearl, so it could be the cartridge. Just a suggestion.

Forget MM cartridges! None of them sounds as good as even the venerable Denon 103 (and its variants)! These have always been my go-to choice for a budget price! When I wanted to add a NEW TT to my collection of vintage TTs I bought a Pioneer PLX1000 direct-drive, Denon 103R and a vintage Denon step-up transformer (SUT). Cost ($700 + $300 +$200) = $1200 for a rig that easily competes with far more costly gear! 

The Pioneer PLX1000 is the hands-down winner in the sub - $1K TT category! Ditto for the Denon 103 mc in below - $500 cartridges!

Forget MM cartridges! None of them sounds as good as even the venerable Denon 103 (and its variants)!

This is funny, ever heard Denon DL-107 MM that was a broadcast standard before they designed DL-103 MC ? Same brand, just MM, no need to pay for SUT.

If you like conical stylus and low compliance over a decent MM/MI design then you’d better listen to AM radio (Denon was designed for broadcast in the 60s). The OP asking for high resolution, not a rolled-off oldschool sound of Denon DL-103.

The problem with your DL-103 is that you do not even use it on the right heavy tonearm, instead, you’re using it on lightweight tonearm designed for MM (or mid compliance MC).

Another problem with DL-103 is a short life span of the conical stylus (300 hrs) and the cost of re-tipper job, who will glue a new tip on aluminum cantilever. This is a degradation, because the original tip does not have a glue and was pressure fitted. To get equal sound the re-tipper must change the whole cantilever. This is a waste of time and money.

Even a much better LOMC cartridges can’t beat some killer MM or MI.

The MM/MI always cheaper, stylus is user replaceable, life span of the tip can be 600 or even 2000 hrs (depends on the profile).

Also the OP does not have an arm for low compliance MC anyway.

All the typical MM cartridges (Shure/Stanton/AT/Ortofon ...) have coil inductance measured in HUNDREDS of milli-henries! This rolls off the high frequencies and slows transient response. Hardly what can be called "high fidelity"!