How would you spend my next $5K?

Consider denoting it to the needed people.  I don't think you need to add / change anything further to your system.  Just enjoy the music.

Looks like you have a very nice setup, I’m a little behind you but, have similar equipment and just popped for a good DAC that’s on the way.  I don’t know how you can best spend the next 5k but, I have a question if you don’t mind. I have same front end Innuos but missing the PHNET. Does yours drastically improve the SQ in your system or is it negligible? In other words, would you do it all over again knowing how much better it is?

@hysteve Thanks.  I got a both USB and NET used, elsewise would not likely have sprung.  NET seemed to make a bigger difference although that may be because I got it first.  Deeper blacks. A more “settled/relaxed sound” and somehow a better grip on bass though I don’t know why that happened.  Innuos says  NET+USB get Zenith MK3 to 90% of previous pre Next Gen Stmt.  

Room treatments are what 90% of audiophile systems are severely lacking.

Otherwise, I recommend you spend the $5K on contact enhancers, fuses and voodoo shaman chicken bones. 

A second sub made a huge difference in my room so that would be my recommendation