OP,
looking over your system… sort of anchoring on your speakers. I would say complementary components (if carefully chosen) would be about $5K each. For a Phonostage, I would go used. Audio Research PH8 would be my choice, or new Pass XP17, or Presto.
My strategy, if I were you, would be to swap my components to be up to the level of my level of speakers. Hence, I would upgrade with the objective of taking me out of the market with each purchase. So, the phonostage should take you out of the market. I would you upgrade your TT next, this would net you a substantial gain. Your integrated amp is probably at the level of your speakers. So, that would be at an optimal level.
Typically, I’ll live there for seven to ten years until my financial situation improves and I can think about the next level.
FYI, I own an Audio Research Reference 3. I brought home a ARC Reference 3SE this weekend to audition. Very notable improvement. So, I will send mine back to the factory to upgrade it to SE. clearly worth the money.