Your D-700's are indeed quite good and if you're not getting great sound from them, it's not the fault of the speakers. The big Tannoy's do extremely well with tube amps and quality integrateds, but they will really open up with a high current ss amp that's at least 200 wpc. McIntosh and Tannoy are a classic combination, there is great synergy between the brands, but MAC gear might be out of your price range. Here's some suggestions that might be in your price range: Classe CA-200 or CA-201; Audio research 100.2; Audio research D400 Mk2; Gamut D-200; Plinius 9100 or 9200 (integrateds).
I think your D-700's will do better with the best 2 channel amp your budget will allow, rather than trying to get a 5 or 7 channel amp and stay in your budget, as you will again be making sonic sacrifices and again, not getting as much as you can out of the speakers. You'll just be in the same situation as you started with. You can always add a 3 channel amp later on for HT as your budget allows.
Good Luck to you,
Mike.