I am not familiar with the NHT. However, I have recently had an eye openning experience regarding amps for bass and sub-bass extension.
I think that there are very few absolutes in Hi End audio. Most are very system dependant and this may be one of them. Over the years I have had several friends try different amplifiers for bass in biamped systems. These systems are similar in that they involve the larger Infinity line source arrays of bass drivers in seperate towers.
I have always used the venerable line of Bryston ampifiers on bass and have never looked back, until just recently. My friends have also tried Bryston along with just about every respected brand of amp known for it's controll of those lower regions. Were talking top of the line Krell, Mark Levinson etc. Long ago they settled on the mightly, but more slight John Iverson Eagle IIa for it's superior control on those Infinity towers. Over the years they tried trying to tell me what I was missing, but I was quite content with my Bryston and quite pleased with my low end performance.
Well, finally I gave in and picked up an old Eagle IIa for around $350. I installed it in my system and was instantly floored at the transformation. It was not a small change, but quite substantial. From this less efficient amplifier I am getting more apparent bass that is tighter, more well defined and has such an iron clad grip on my bass towers that it must be experienced to be believed.
I guess what I am saying is that if you are looking for not only a good amp for a subwoofer, but one that may actually be one of the very best available, period, then it would be worth your while to seek out some used Hi Fi sites for an Eagle IIa. The passing years and technological improvements do not seem to have improved upon it's bass performance.
