Newbie - Which USED Amp & Preamp for under $2500


My preamp has seen better days and is sounding awful. My amp is pretty weak too. I have $2500 to spend and I need help. I've been looking at the following, any advice would help:

PREAMPS:
Audio Research SP17L Tube Preamp
Quad QC24
Arcam c30

AMPS:
Arcam PI monoblocks
Conrad Johnson MF 2250
Bel Canto Evo 200.2
Quad 99
Perraux 200P
Refurbished McCormack DNA 125

Below is my current setup. I plan on upgrading my speakers in the near future, so I'll want something that will work now and later:

Hafler 9130 amp (x2)
Adcom GTP 500 Preamp
B&W 602 series 3 Speakers

Thanks!
mmrump
Darkmoebius, Thanks, I have a couple questions...there is a Bryston 3B-ST available locally for $750. Otherwise there is a 4B-ST on Audiogon for $1350. Is the 3B something to consider, or is the 4B definitely worth the extra $$$?

I've heard a lot about the Mccormack DNA-125. Should I be concerned about the age of this amp?

In brief, what are the downsides to class d amps?

Would you recommend the Odyssey Stratos Extremes dual?:
http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1260018001&/Odyssey-Stratos-Extremes-Dual-

Thanks, this is a HUGE help
The Cary IA write-ups seem very positive for jazz, blues, classical. Are there other recommendations for specific IA's in this price range? What is the benefit of IA's over separates? Thanks!