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 second stringreen. Johnny R is a good man to talk to. His Agon name is 'audioconnection'. PM him.
The comments about interconnects are also another way to change the sound of your system, though you will need to research and trial many in order to come to some understanding regarding their appeal/detraction in your system. Johnny R could also help in this matter.
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" 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.