The NAD 2100 landed in 1985 as the company's answer to a simple question: what if you didn't need a preamp integrated into your power amp? What if you just wanted clean watts, reasonably priced, without the marketing theater? NAD had already built a reputation on this exact philosophy—good design, honest engineering, no unnecessary noise. The 2100 took that ethos and stuffed it into a compact chassis that looked more like a heat-sinked brick than a statement piece, and that was entirely the point.
One hundred watts per channel into eight ohms. Not 120. Not 150. One hundred, measured conservatively, because NAD believed in specs you could actually trust. The circuit is relatively straightforward—a complementary-pair output stage built around discrete transistors, with what NAD called their "Soft Clipping" circuit to gently compress the signal before hard clipping could happen. In practice, this means the 2100 will push into difficult loads without sounding angry about it. The power supply is robust without being extravagant: a toroidal transformer, decent filtering, and the kind of bias stability that doesn't require constant tweaking.
What makes the 2100 feel special now, nearly forty years later, is precisely what made it feel unglamorous then. It's a power amp that sounds like power, not like a preamp pretending to have personality. You run a preamp or receiver or DAC into it, and it gets out of the way. The midrange doesn't have that slightly compressed, slightly sweet character of some of the warmer Class A amps from the era. There's no tube glow, no exotic topology, no story to tell at dinner parties. What you get is even gain, clean headroom, and the kind of reliability that means people still own these things and don't think much about replacing them.
The 2100 will handle four-ohm speakers without breaking a sweat—push it to maybe 160 watts in that territory—and it runs cool enough to sit on a shelf if you need it to, though NAD sensibly included rear heatsinks and ventilation slots. This was before Class D got cheap enough to matter, before switching supplies became the default, back when making an honest Class AB amp just meant doing the math right and not skipping the parts budget.
The honest caveat: the 2100 doesn't do anything you can't get cheaper now, and plenty of modern Class D plate amps will outperform it on paper and probably in your room too. If you're buying new, don't. If you're buying used at three or four hundred dollars, you're buying consistency. You're buying something that won't surprise you or demand your attention. Some people find that boring. Some people find it perfect.