Will spend $ 2500 for used speakers for upgrade.

I bought a pr of the Von Schweikert VR4 Gen III for that price, I would also look at Aerial Acoustics 7b, and Tyler Acoustics.
Best of Luck

There are two pair of Soliloquy 6.5s on sale here on Agon. These are the top of the Soliloquy line They retail for $6,500 and they are listed for $2,250 to $2,700 here on the Agon. I have the 6.5s and I like them alot. There are also Silverline Sonatas on sale for $2,200. There are a bunch of speakers out there in that price range. Good luck.

I don't think you'll find used N803's for $2,500. If you do, and they
check out -- snap them up! In that price range, used. I would
recommend auditioning Sonus Faber Grand Piano Homes, Revel F-30's, and Monitor Audio Gold Reference 60's.

Dunlavy 4 or 4a would be bettered

I agree with RSbeck, you won't find 803's for 2500. I also agree that the Revel F30 would be an excellent choice.