classe Dr-3

I've always loved Dave Reich's superb early designs, but they are pretty old now. If you're thinking of a DR-3, you might consider the new Aleph J from Nelson Pass at First Watt. It has the same power as the DR-3, but is a modern Class A design. I'd be willing to bet it sounds better than the older amp as well. The early Classe designs sounded pretty dark. For under $2500 you simply can't go wrong with the Aleph J. It's the best low-power solid state amp I've ever heard. I have a review here at:
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1132102991

The DR-3 would definitely be a few sonic notches above your NAD amp. Succinctly put, the Classe is in a totally different league. They were considered one of the finest sounding transistor amps in their heyday. They were famous for being able to drive the toughest loads with ease despite of their low wattage. If you can find a used one in good condition, I say go for it! That's just my two cents...

Good Luck

Drive tough loads is right. I once heard a DR-3 VHC (the big brother of the DR-3) kick a Krell KSA-100 into the weeds driving a pair of Apogee Divas. That was a phenomenal experience - Liszt's "Via Crucis" turned one end of the store into a cathedral with that amp. The Aleph J will not have the low-impedance drive capability of the DR-3 by any stretch of the imagination.

One thing to keep in mind is that the electrolytic caps in the old amp may need replacing at this point.

You can still send the amp to Classe if it needs any repairs. A killer amp, wish I would have bought one when I had the chance. You will notice an increase in your electric bill and you might not play it much in the summer.
I don't think there is a speaker it will not drive.

Gliderguider is right i owned a Classe DR3-VHC that stood for very high current from 1988 to 2000 when i sold this amp it was because i was moving in to a condo and my system was to big for the smaller place this amp only drove difficult loads 4 different pairs of Acoustat's speakers from 82db to 85db this amp had a minimum of 18,000 hours of use and the only money i spent on it was for WBT rca plugs and big electrical bills all this time it was matched with Classe DR-7 preamp Conrad Johnson premier three and the last one was a premier ten the DR-7 was a very good preamp but i prefer a tube preamp with solid state amps i'm a smoothy kind of guy i sold this amp the same price i paid for it in 1988 and the guy that bought it was very happy ( me too )