Upgrading from a B&O RX2. Help.....

I've been reading all the great advice on this site and I'm still overwhelmed! I bought the RX2 in 1988. After a few new cartriges it still sounds sweet on my Polk SDAII's that I also purchased in '88. I've recently picked up a CJ 2300A some decent IC's, speaker cables and an Adcom 565. What an incredible jump in sound quality from my mid level yamaha power and pre, also '88. I have been officialy bitten!! I'm listening to my mid to late 70's album collection again. Journey to Love never sounded better.
Anyway, my dilemma comes down to upgrading the B&O.

1st: Will there be that much of a difference, from the RX2, if I went tooooo say an MMF5, or that price range? I have yet to get out and listen to what's on the market for comparison.

2nd: I'ld like to even consider 1k and under. VPI Jr., MMF7 or Rega. The dilemma with this question is compatability with the 565. Undeniably a decent mid price phono stage, but would the sound through the Adcom be worth the price spent on the table? I would have to think so from the review Stereophile gave this unit.

I'm obviously not well versed in Audiophile lingo and am quite happy with my meager system. Nak BX300 tape deck and Teac PD350 CD player, which is the next upgrade, round out my '88 system. The purchase of the CJ blew me away. The sound that came out of the 17yo Polks kept me awake at night thinking about all the years I considered making a move and didn't. These speakers really are increadible. I don't know what direction Polk has gone, but they don't make em like that anymore. Thank you for listening. Any and all advice is greatly appreciated.

Brad