Your gear is mostly still extremely nice by today’s standards. You obviously put a lot of thought into system building. After checking into the condition of your styli (potentially upgrading to a new MC cartridge), I’d look hard at the PS Audio phono preamp - a $1K preamp from so many years ago should have numerous options today for significant improvement. It could absolutely be the weak link of your system.
I don’t know much about the TNT turntables and their versions. My dealer had one as his personal table for a while before upgrading to a Clearaudio innovation Master, and it seemed quite nice. I seem to recall reading some posts about such-and-such version / configuration being much better than this-or-that, so significant research is warranted before making any moves there. With VPI, newer does not necessarily mean better, so definitely proceed with caution. The ET 2.5 arm is quite nice, fortunately you don’t have to suffer with a VPI unipivot :) And I think Supexes were the basis for Koetsu cartridges so if in good running condition should be quite nice too?
I don’t know much about the TNT turntables and their versions. My dealer had one as his personal table for a while before upgrading to a Clearaudio innovation Master, and it seemed quite nice. I seem to recall reading some posts about such-and-such version / configuration being much better than this-or-that, so significant research is warranted before making any moves there. With VPI, newer does not necessarily mean better, so definitely proceed with caution. The ET 2.5 arm is quite nice, fortunately you don’t have to suffer with a VPI unipivot :) And I think Supexes were the basis for Koetsu cartridges so if in good running condition should be quite nice too?