I have a Thorens TD-166 MKII, with a Thorens TP-11 MKII tonearm (TP 62 armwand and non-removable headshell), as well. I bought it (with my parents help) while in high school (circa 1977). I was using the same Signet cartridge before mothballing the turntable for @ 15 years. In 2019 I broke the turntable back out, had it gone over, and replaced the cables and replaced the Signet cartridge with an Ortofon 2M Bronze "Verso." You may want to consider this cartridge. The Bronze stylus can be upgraded to the Black. Ortofon’s "Verso" versions of the 2M series of cartridges are specifically designed for the original Thorens undermount system (screws go up from under the cartridge and into the underside of the Thorens headshell). Very handy. The whole thing sounds great.
turntable upgrade?
Though I primarily listen to Qobuz, I have enough albums that I still desire to maintain a good analog set up. As I have upgraded the rest of my system, I'm wondering if my longtime Thorens TD 166 mkII and/or Signet TK5e may be overdue. Would a Pro-Ject Debut Carbon Evo be a noticeable improvement, or would I need to go another step up (my budget would be up to around $1000)? If I replace the cartridge I'm thinking a Naga MP-110 or AT-VM95ML. I welcome the thoughts from anyone with experience with these.