Best Bang for Buck - Time to Upgrade

Dear Audiophile,

I would love to hear opinions rendered on the most cost effective way to upgrade my current system. After many years of complacency I am feeling the need for a tune up.

Here's the set up:

AR Classic Turntable with Grade signature MM cartridge
Rotel 855 CD player
Proton Tuner
Audio Research SP 6E with mods (sideral caps, gold rcas, upgraded power cord)
Quicksilver KT 88 monoblock amps
Vandersteen 2CE signature speakers/sound anchor stands
Discovery interconnects and bi-wired speaker cable

I am tempted to pick up the bargain Oppo cd/dvd player as technology has probably improved quite a bit since I bought my cd player. Otherwise I am open to suggestion.

In terms of my listening preferences it includes a lot of rock, blues, jazz and a sprinkling of classical.

The recordings that always sounds best on my system are the Chris Isaac album called Heart Shaped World and the Miles Davis album Kind of Blue.

Thanks for your help!

Alex