You have system hardware that probably couldn't be improved enough to make the extra costs worth it. On the other hand, playing around with the listening area may not even have to cost much to bring about significant improvements. Once you know how to control the room, you can then, perhaps, profitably experiment with some hardware changes (remembering that speaker changes will require further analysis of the room). Cartridges are a good place to start--they provide a much quicker education on differences in sound than other components. If you can't hear a difference between cartridges, you probably won't hear differences between other components. Of course, cartridges interact with arms in many ways, so you may find yourself experimenting with arms, as well. Maybe it's better just to sit back and enjoy the music.
How good can it get, really? - my stereo sounds amazing!
I really love my stereo currently. I keep thinking I should be looking for the next piece to upgrade - phono stage, stereo subs, etc., but honestly not sure what to change or why I’d potentially spend more money to achieve a result that’s lesser or equal to my current sound quality. I sorta feel clueless as to how to proceed without screwing up what I have. I know it can get better but honestly I’m at a place when I just don’t know how it can. Hmmmmm.... not a bad problem I guess. Open to suggestions for sure. Thx.