I started out with a Rega RP6 and Fono phono stage. Then I got all the Gove Tracer platter, subplatter weight stuff. Subtle but good change. Then I got a Denon 103R to replace the rega Exact cartridge. Moderate to mild change. Then I got the Allnic H1201 phono stage. Big change. Then I pulled the motor off the plinth and remote mounted it. Huge change. Then I broke the RB300 arm and got a Vertere Arm. Mild change. More a shift. Then I had the Denon cartridge upgraded with the saphire cantilever and line contact diamond. Big change. In all that my plinth material and configuration changes a few times. Each a mild to medium change. Some bad some good.
My overall take. The cartridge and phono stage are a big deal. The table and arm less so, but still very important. I have not messed with cables much.
I also built a vacuum record cleaning system. Clean records are a night and day improvement. It has to be done. No question. Even a brand new record has form release oil on it. Clean every record with correct liquid and vacuum them. Look up how to do it. Use good cleaner. Regular soap will leave build up and catch more nast creating worse problems.
This is just my phono Odyssey.