turntable upgrade?

If the Thorens is working up to spec you will be hard pressed to beat it with a $1000 *new* turntable. Are you using the stock tonearm? Perhaps consider mounting a SME or other tonearm. Check the Vinyl Nirvana website for more options to hot rod your TD-166.

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.

FWIW, The phono preamp is as important as the TT & tonearm. Don't know much about yours but its importance is often overlooked.

xs1137, I have used a VM95ML in my system and I am usually using cartridges in the 2-5 thousand dollar range. I use electrostatic speakers with subwoofers. The VM95SL is an amazing cartridge for the money. It is a good as many cartridges costing 3 to 4 times as much. It will go perfectly with your Thorens. No need to change it at all unless something is broken. 

Thanks for the input so far!

The Lounge phono stage is very well reviewed for it's price range (under $400), possibly it (and/or the cartridge) is a weaker link than the table?  I would like to get my analog end to sound at least as good as my digital end does.