Well, I don't think I'm going to say much new here, but I think the best upgrade is always in the speakers (to a point). Good speakers will sound better through crappy electronics (in general) than crappy speakers through good electronics.
But given your price range, and what you current own, then changing out your Denon might yield the best results. McCormack is a SS amp that's known to have sound close to tubes. Used DNA-0.5's are close to your price range for an amp ($500-$700). The other suggestions are good as well. But that doesn't leave you with much funding for a preamp, but you could run your Denon as a preamp. Does this defeat some of what your trying to accomplish in bettering the sound, I don't know, but you could try it.
The Musical Fidelity A-2 was a good amp and can be had for something in or under your price range, and was a very good integrated when it was released. The thing with an integrated setup is that you have to either be willing to discard it if you upgrade, or be satisified with the sound for a long time. Integrated, IMO, are good for secondary systems where you aren't going to be as critical.
I think you can find a preamp and amp you are happy with in the price range you are looking.
Preamps to consider:
NAD 118
McCormack TCL-1
Conrad-Johnson PV10/PV11
Amps to consider:
McCormack DNA-0.5
Rotel RB-980BX
Forte 4A
I'm not as familiar with tube gear, so I'm afraid I can't offer much there.
Basically, you need to really demo equipment (in your current system, if possible) and decide where you get the best bang for the buck. Don't bother listening to anything outside of your price range. What you want to see is if there is a noticable difference between what you currently own and what you can afford to purchase. Yeah, a $20,000 CD player might sound good, but does it sound $19,500 better than what you have? And since your budget can't afford it, why listen to it?
Don't bother replacing your cables. There is a lot of noise about cables, but even the real professionals argue over the benefits. Look on the internet for DYI speaker cables if you think you really need an upgrade there.
Hope something I said might help, and best of luck!
But given your price range, and what you current own, then changing out your Denon might yield the best results. McCormack is a SS amp that's known to have sound close to tubes. Used DNA-0.5's are close to your price range for an amp ($500-$700). The other suggestions are good as well. But that doesn't leave you with much funding for a preamp, but you could run your Denon as a preamp. Does this defeat some of what your trying to accomplish in bettering the sound, I don't know, but you could try it.
The Musical Fidelity A-2 was a good amp and can be had for something in or under your price range, and was a very good integrated when it was released. The thing with an integrated setup is that you have to either be willing to discard it if you upgrade, or be satisified with the sound for a long time. Integrated, IMO, are good for secondary systems where you aren't going to be as critical.
I think you can find a preamp and amp you are happy with in the price range you are looking.
Preamps to consider:
NAD 118
McCormack TCL-1
Conrad-Johnson PV10/PV11
Amps to consider:
McCormack DNA-0.5
Rotel RB-980BX
Forte 4A
I'm not as familiar with tube gear, so I'm afraid I can't offer much there.
Basically, you need to really demo equipment (in your current system, if possible) and decide where you get the best bang for the buck. Don't bother listening to anything outside of your price range. What you want to see is if there is a noticable difference between what you currently own and what you can afford to purchase. Yeah, a $20,000 CD player might sound good, but does it sound $19,500 better than what you have? And since your budget can't afford it, why listen to it?
Don't bother replacing your cables. There is a lot of noise about cables, but even the real professionals argue over the benefits. Look on the internet for DYI speaker cables if you think you really need an upgrade there.
Hope something I said might help, and best of luck!