Needing fixing because it was broke, at least here, was the treble; not its actual performance but class D predictions. This breed, deservedly I think, gets often called out for its inferior top end. Be it subtly wiry, steely or dull and not sufficiently extended/airy, a common consensus is that bass prowess isn't mirrored on high. From bells to gongs to cymbals to triangles; from massed strings and chorus in reverberant acoustics to muted trumpet, pan flute and violin flageolet; I set the bloodhound puppies on the HF trail. They came back exhausted but happy. When fed from properly wideband ancillaries (DAC/pre or DAC + pre), the Nord monos had to make no excuses. Being lit up all over included the treble. In fact, the tracking of wispy decays, hall trails and overtone swirls like smoke on the wind were a particular forté. It was directly responsible for that inside-out sense of illumination and spaciousness. At the bandwidth's opposite end, the same qualities appeared. This meant no chiseled granitic but naturally behaved bass. My only minor complaint at least with the bigger SI opamp was lesser bass power than the massive output rating promised. I take elegant bass over cyborg or elephantine low freqs any day of the week but good ol' greed would have wished for just a bit more oomph. For that you want the Sparkos. You'll simply pay with some illumination and subjective speed. Because those are such outstanding attributes, one could feel ill-inclined to give much if any of them up. Choices!


Quick Q&A. • Why did you focus on hard-diaphragm speakers when, being voiced along the same lines as the amps, they risked overexposure of shared qualities?
Precisely because class D preconceptions, if true, were most likely to be caught out by such loads. The fact that it worked so well became the most telling proof to the contrary. Plus, Kharma loudspeakers had, for a while, class D amplifier colleagues in the same catalogue. There's no conflict by design.
• Did you encounter any turn-on/turn-off pops as you and Marja & Henk experienced with a competing design?
None whatsoever. The only thing to hear is a small mechanical relay click.
• As very powerful amplifiers, did these have to play loud to come on song?
Quite the opposite. Because of their very low noise floor, they behaved like high-efficiency speakers. When you turn down the volume, the quietest data eventually fall below the noise floor of the room or gear or are fully masked by louder sounds to become inaudible. Very quiet amps with superior low-level retrieval like these delay that threshold to be ideal hifi whisperers.
• Do these need to stay on to sound their best?
No, standby is fine but they will take about 15 minutes to wake up fully.
• So they run completely cool?
The chassis get very slightly warm; just enough to notice.
• Can I use the stock power cords to get started?
To make sound, absolutely. To sound their best, you'll want something better.

•Will I need a power conditioner?
Impossible to predict. Again, these amps are very sensitive to their power feed. Experimentation is in order. At 90%+ efficiency, they don't draw much power. But they respond very obviously to changes/upgrades on the AC line. Perhaps it's a 'backdoor' function of how much noise from their switching power supplies injects into the AC loom to affect the other components. This would be related to resonance control whereby acoustic sound pressure and the speaker's mechanical jackhammer effect on the floor migrate into the component stack to influence the behaviour and sound of that gear. Disrupting resonance pathways can improve the sound. Perhaps better filtering on power cords and conditioners improves class D sound in a similar manner by closing a backdoor?
• Is it difficult to swap opamps?
If you can screw in a light bulb, you can roll opas. You'll have to get underneath the flying lead to the XLR connector, orient pin 1 correctly as per the included instructions, align the pins, then carefully push down. To lift out, pull up by the bottom not top plate.
• I don't have balanced cables. Can I use RCA cables with an adaptor?
You can but proper XLR cables worked better for me.
• I'm also considering ICEpower amps. How do these compare?
Proprietary input buffers can change/steer the stock modules so there is no fixed ICEpower sound per se. The Wyred4Sound ICEpower amps I tested were warmer and denser, the Gato Audio Pascal-based DIA250 even more so. Amphion's Anaview amp was the exact opposite and well cooler than the Nords. The closest class D competitor in recent memory would be the Digital Amplifier Co.'s Maraschino monos.
• You referenced the Job 225, Crayon CFA-1.2 and Bakoon AMP-12R. How exactly do these compare?
Aside from being vastly more powerful, the Nords belong to the same general sonic school or aesthetic. On sophistication, they sit between the Job and Crayon. The CFA-1.2 and AMP-12R have the even more refined and airy treble. On load tolerance, the Brits beat them all. On price, only the Job is more affordable.

uCD vs. nCore. Because this A/B much favoured the Nords, we won't beat up on two bloodied monos except to say that the AURALiC Merak were clearly drier, duller, matter and somewhat monochromatic and grey by comparison. Whist armchair pundits would latch onto their linear Plitron-transformer power supplies as having to be superior to the Nord's SMPS, actual auditions turned those tables. If class D has indeed undergone evolutionary changes as it seems, then these Nords were a few generations removed from the older Meraks and up by an octave or two; or Nord's buffer alone made that much of a difference. Not only did their NC500 SE monos cost less than half, they clearly sounded better. Sometimes progress isn't SET-style marketing THD but real.

A reader: "About Bruno Putzeys' NC1200, another room at the event had the nCore-based Jeff Rowland 825 with Mårten's Mingus Quintet speakers. Earlier, the dealership's owner had already compared the Jeff Rowland to the Mola-Mola Kaluga. He listed for us which aspects the Jeff Rowland improved upon. When he told Bruno that there was a better implementation of his nCore modules, Bruno told him which aspects he felt the Mola-Mola could be improved upon. These were exactly the same improvements Guido had already listed in his comparison. Bruno turns out to have a very good ear and internal reference for amplifier sound." Nothing is perfect. Everything is designed to a price. With the Nord, we don't play with $32'000 and 160lbs. We make do with 1/10th the budget and less than 1/10th the weight yet enjoy identical power specs. Are we sacrificing 90% performance? 50%? 10%? Are we already better than the stock Hypex buffer circuit used elsewhere? These are open questions. They salt this conclusion to proof it against absolutism.

Nord Acoustics website