Best Amp & Pre-amp combo for under $2000 ???

Are you just using 2 speakers for both HT and music?
Well for a simple practical "solid state" solution, you'll not go wrong with the Parasound amps on those! A good classe SSP25 or 30 pre/pro, and you'd be set IMO. I've sold the Def tech's for some time, and the Parasounds in the past. For an affordable combo, you'll not lose with the Parasounds. The Def Tech's have a bit of top end tilt, and are kind of "cool" sounding. The Parasound compliments that well(kind of like the Bryston amps), with it's slightly rolled off top end and warm bodied, although clean, pressentation! The combo balances out well.
Also, the Classe amps do superb in that regard as well, with slightly limited top end extenstion and good body(slightly better than the Parasounds).
If you want to get "perfect" and "tricky" you could go "tube amp"(like used VTL ST85 amp), get a fantastic soundign used Classe SSP25 pre/pro, and maybe later upgrade your 2 channel with a better tube preamp!(looping the pre/pro through an AUXILARY input on your 2 ch pre! However, the Classe pre/pro is clean enough that you'll likely not even worry about it. Plus teh Classe SSP25 has "dirrect analog inputs", THX, and superb digital dacs! that piece I have yet to hear it's sonic superior in a Digital pre/pro for the money!!!!
good luck

My best experience was an Audible Illusions Mod 3 preamp and the Aragon 4004 MK II amp. It actually was better when I changed the Preamp to the Kora Triode preamp with the Aragon. It increased the bass response and was more "musical"......I have since moved to Audio Valve gear now but the little Kora is a sleeper and holds it's own with much more expensive preamps and is not that far removed from my new AV Eklipse which costs much more........those pieces should be around $1600 together

It's a no brainer, the Odysey Audio stratos stereo amplifier with tempest preamp. The musicality of the this system is absolutely intoxicating. If you don't like it send it back for a refund.