It's difficult to see how cables can be responsible for that much volume loss. I'm not saying you are wrong, it just think it may be something else. I'm not too familiar with your equipment, but if you have any settings on your phono preamp, you may want to try them. One very common mistake is when someone sets the phono preamp for MC when they have a high output MC cart. If that's the case, it needs to be on the MM setting even though its a MC cart.
I think it would be a big help if you tried the 2 carts. that you used with the Thorens and mount them on your other TT that you know is good. If they work OK on that TT, you can eliminate the phono pre altogether. That would really narrow it down to the cables in question.
I think it would be a big help if you tried the 2 carts. that you used with the Thorens and mount them on your other TT that you know is good. If they work OK on that TT, you can eliminate the phono pre altogether. That would really narrow it down to the cables in question.

