New or old Thorens?

This is great advice and much food for thought. Thanks @elliotbnewcombjr

ill look into these arms for sure  

Also 3 arms on a turntable, that is pushing the envelope! Good work. 

I bought Acos Lustre GST-801 based on advice here, it is amazing, and this looks like a terrific opportunity, I’m tempted to make an offer to have a spare

Unique magnetic tracking force and magnetic anti-skating, and superb VTA on the fly.

it fits thru a simple hole, no special cutout involved, easy din cable connection, done.

you could easily put it on your TD125, or buy it, and find a Tt it can go on.

You could put a different height adjustable/removable headshell arm on your TD125, 

this Acos Lustre CST-1 is highly respected and of great value

GST-1 arm boards for your Tt readily available

black or white, possibly others

I would go for a new turntable, but not limit it to Thorens.

I always want a removable headshell for various cartridges, you have several.

Or a table that allows 2 tonearms. I squished a 3rd arm on mine, see 8th photo here:

I ended up with mine as a result of searching for a longer tonearm.

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Also, easily changing tonearm height. VTA on the Fly while adjusting is one thing, but just easy height change is a great feature: cartridges are different heights, so change the headshell, easily adjust the tonearm height, then tracking, then anti-skate.

Multiple arms, that’s all done, so switch between cartridges instantly in a listening session, i.e. two or your favorites, or one stereo, other mono ...

Technics 500 tonearm base is superb for easily changing height. It can receive a straight fixed cartridge arm and an s arm with removable headshell

here is a technics combo like I just helped my friend put together, it's a SP-25, his is an SP-15. note: sp15 also plays 78, sp-25 33 and 45 only.

Here is a Technics SP15 with 500 basse with the straight arm

Here’s one with the same base with the S amr, they change very easily,

hers’s the s shaped tonearm that fits the technics 500 base