First "audiophile" system, now what? Suggestions for best "bang for the buck" upgrade?


After being beguiled with mp3s and the TV AVR, I finally realized I missed having a dedicated stereo system. With a budget of $2400, here is what I put together:
  ProJect Carbon 1 w/TizoAcrylic platter and Ortofon Red cartridge,
  Hagerman Bugle2 preamp,
  Vincent V-60 tube amp,
  Martin Logan 12 speakers.
 No special wires or cables. My room is 14x19 that is open to the kitchen. Compared to what I had been hearing, this system sounds fabulous. But now I want more fabulous. So I am writing to seek help on making short term/long term plans to upgrade. Short term means the biggest improvement in sound that costs $500 or less. The long term plan could cost maybe $2-3k or more. I have read that going from Ortofon Red to Blue might be a an inexpensive but very noticeable improvement? If speakers are my weak link, then maybe Martin Logan electrostatics would be good (when my ship comes in)?
I welcome any suggestions.
128x128etwilley
" I have no problem with vinyl, was buying Japanese in 1980 and still have my 35 year old JVC QLY5F.  But I sold most of my records and only keep it around to demonstrate to friends that the best digital today sounds ....analog."

What "best digital" are you demonstrating to your friends? 
Your analog reference for this comparison is a QLY5F...?

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I'm just saying that to present digital to your friends in combat with analog then it should surely be the Vivaldi 4 box system from dCS...with of course suitable cables. Additionally it is not sufficient to represent analog with a QLY5F. 
I wasn't even born in 1967 so fair play to you sir for building an amp.
You have been given a wealth of great advice already. I will say in 35 years in this wonderful hobby, the biggest difference maker in my systems has always been speakers. Amps, yes. CD players, yes. Cartridges, to a point. The room, certainly! However that's a bit tricky to tackle with a family and real world issues. Personally, I'd look to speakers first that are compatible with your amplification....

I’d save up for better speakers. Lots of options open up when you have $2k to spend. Also - don’t limit yourself to just Martin Logan.