If you are looking at Bryston - get the 4B-ST - its a great piece and can be had used for around $1600. Pass on the 3B-ST - not enough power for your speakers IMHO. I've owned 4 ohm speakers (Acoustats & Maggies) for the last 10 years and my old 3B always ran out of steam. Not enough to shut down like your NAD but it would start to clip. The 4B gets a little warm but never strains.
Amp overload,! NAD 2600 & maggies 3.5
I got a pair of magnapan 3.5's two months ago and paired it up with the NAD 2600 power envelope amp (150 watts) and a NAD pre-amp series 20, I cannot put the voloume above 4.5 without the amp overloading. Any suggestions? Having the song crap-out every 10 seconds kind of ruins the mood.