Amplifier to pair with NHT 3.3


I'm the proud owner of a pair of used NHT 3.3s. From what I've read I should be feeding them with something capable of plenty of power, but I've got them running off a small crappy integrated amp (30W) at the moment. Any suggestions for an upgrade? I'm looking in the < $500 range for something used. Thanks in advance.
baldeep
Used ... a NAD C370 or C372 (there's a C372 new for $625 on Audiogon now).

Regards, Rich
For $500 or less, a used Adcom GFA-5500 has 200 watts per channel into 8 Ohms, so it would be even more than that into the 3.3's 6 Ohm load, and it is a Mosfet amp, which is supposedly a little warmer sounding than bi-polar designs.
Just bought a Crown xls2500 because of good net reports on it and others in various blogs on their drivecore series. I used it to replace an excellent B&K 202+.

Cost new under $600 from local Guitar Center with a free return policy. Less on Ebay.

Result fantastic sound. Can hardly believe it isn't a $12000 Class A amplifier. No white noise even with my ears next to the tweeters and I can't hear the fan even when it comes on and I'm next to it.

I have never before heard such well controlled bass and sweet highs coming in combination from a solid state amplifier into none set speakers. The sound is neutral and flat with no coloration. I loved my B&K's but I have to believe my ears more than my prejudice against pro-audio gear. Check them out, they drive over 400wrms per channel into 8 ohms and almost twice that into 4 or 2.
I just wanted to add some thoughts about using a professional music amplifier and in particular the Crown XLS Drivecore series. (XLS1500-XLS2500)
1. An S/N ratio of 105db A-weighted, though very good, isn't for very High efficiency speakers (It works out fine with the NHT 3.3 at 87db efficiency and even my Taddeo Monitor 1's at 92DB but I doubt it would work well with speakers rated at around 100DB or better as I think you could start hearing too much white noise.
2. Even though these particular Crowns have RCA inputs they need a higher level from your preamp (1.4vrms or better in order to reach full volume capability)than many preamps put out so check your specs.
3. I strongly recommend leaving the amps built in speaker protection turned on as it works very well and these amps are very powerful!

I still love mine and although an $8000 Krell pure class A might be better? I simply can't afford to find out. But it does sound better than an excellent 6550 based Bewitch tube amp driving my efficient old Taddeo's in either triode or pentode mode to my old ears. It just seems to grab the driver's and absolutely hold them to its will.