Can I get some upgrade recommendations for my Mitsubishi LT-20

I have my Mitsubishi LT-20 set up with a basic Audio-Technica ATN91 cartridge. Output is sent to a Schiit Mani preamp then to the RCA entertainment system I inherited from my great grandmother.

I understand there is plenty that I can do to on my system past the turntable; I will get to those parts of my setup as my budget allows. On that side I will eventually get a better preamp. As for the entertainment system I am going to try to find a completely reversible way to upgrade the entertainment systems amplifier. Not to mention replace the old paper 6x9 paper speakers with something a bit more modern. I’m thinking something like Focal 6x9 universal speakers would fit nicely.