[Formerly YB-2]

Unfortunately, the answer is not that simple and it "all depends" (which SUT, which cartridge, etc.).
All this said, I think you have plenty of room left with your EAT & Bryston. Try the Ortofon 2M Black LVB as a significant step-up from the Bronze.
For a different flavor, try the Audio-Technica VM740ML. I'm very pleased with my VM540ML.
A couple of other areas that could help are the WireWorld Platinum IC (which I use - again, talk to Ivan) between your TA & Bryston and an HRS base to go under your TT.
If you decide to go the MC route, an HO model will work fine with what you've got and any or all of these upgrades. For a an LO model, adding a SUT will get you there.
As you get to these "better" cartridges, the alignment becomes more critical for optimum results due to their stylus designs (micro-line, Geiger, etc.).