The first thing I would start with is the speakers, Monitor Audio is a great company but with $30,000 to shop with, you can do better. I would suggest something from B&W or Martin Logan, Sonus Farber just to name a few. Having a better source for digital and analog would help tremendously, dump the Sonos for a Aurender or Bluesound music server. Keep the TT and change the cartridge, the Denon DL103 is a great cartridge but its round stylus shape and heavy compliance make it rather pedestrian sounding. Lastly the Subwoofer would be a great place to upgrade, I mutch prefer the REL subs for they connect directly to the amps outputs and blend very well with the main speakers. Have fun! and remember things will only get more sensitive and having high quality source material will matter even more! whether its Digital files or Original great sounding vinyl.
Matt M
Matt M