Rich, I know exactly what you mean. I went through very similar feelings of hitting a wall; spent too much for diminishing gains. I reached a point where even though the system might be 'better' in some audiophile respects, I wasn't really enjoying the music to any greater degree.
A few things helped me. For one, I cleaned house and got rid of things that were fuelling obsessive behaviour more than bringing respite. In my case, I unloaded (horreur!) my vinyl and accoutrements. Yes vinyl sounds better, but the amount of use didn't warrant the storage - and I was buying vinyl I'd never listen to...
Then; major break through - I threw the T.V. and all AV stuff out of the den as well - mostly I just channel surfed anyway.
Downsized to a good CDP with a nice integrated and tasty monitors...
At the same time I did work on some Zen things to try to break that cycle of restless acquisition; enjoy the moment, instead of thinking ahead, waiting on something better to come along...I highly recommend Eckart Tolle "The Power of Now" on that score. The title might sound like the usual pop-psych pap, but it is truly deeper and simpler...
Can't claim a cure, but in remission. Just in case I sound smug...my wife says: "Every time you decide to simplify, it costs me money!"