MrD,
I'm with you. Having spent many years chasing SQ, I am finally happy with my system. Actually two systems in different rooms. I'm not saying there is no room for improvement. The only reason I am happy is because I was able to modify some speakers which will remain nameless. Now I have two pairs modified and "stacked for" for more bass. The rest of the system is average at best, a modest belt driven TT, a AT-OC9 MC cart, run of the mill separate pre and power amps.
Like most of us I went through quite a few amps, speakers and TTs.
Full range stats, JBL studio monitors, tube amps,
I had more than I could use and more than I cared to take with me when I retired early a few years ago. Most of the 10,000 records had to go.
I just could not handle it anymore. I called it downsizing. I can hear the difference in all the amps I had and still have. They were all terrible, tubes or SS. did not matter they all have sound of their own that I could not live with. But the most offensive in my opinion was the speakers. I believe once you get speakers you like, then it's not too hard to find the rest, assuming a certain level of quality. I know many say "front end" matters the most.
Now that I have speakers that do what is important to me, low distortion, deep 3D soundstage, let me hear all the instruments distinctly. The bass is so clean, but I admit not that deep. But then if that bothers me I go into the living room where I have an all Focal vintage 3 way system with 15" woofers in large enclosures. I swap out power amps mostly as I still have a few to choose from. Being retired, I use what I have, which is enough for now.