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So-called think pieces help me think. Doing it out loud in front of an audience clarifies what otherwise might remain odds 'n' ends in that gray murky matter. Coming back from the just concluded München HighEnd show, I noticed something twitching upstairs. Writing it out helped me figure out what it was. I'd met Michael McCormick of Bel Canto Design. They were the first to really fly the Class D for President banner. With well-developed distribution and now 3rd or 4th-gen analog switching amps, they've been repeatedly asked to launch a super amp which on price, performance and cachet would bring the brand mano i mano with Boulder & Co. While engineering at BCD is the domain of John Stronczer, Michael admitted to conceptual issues.


The core appeal of class D with switch-mode power supplies is small - small size, relatively small price. Corporate giants Bang & Olufsen with ICEpower and Philips with uCD/Hypex have sunk such advanced and costly R&D into turn-key modules that the smaller firms making up our high-end sector can't readily compete with their own. Hence the widespread adoption of ICEpower and Hypex boards. Any number of home-audio amps use them. And their numbers are swelling. They might surround the stock boards with proprietary input stages/buffers and custom power supplies, perhaps even swap out parts to market the modules as modified but essentially they remain repackaged/augmented OEM technology. As such this approach is limited to and by what everyone else is doing there. This obviously also limits just how costly such amps can become to remain successful. Who'd knowingly buy a trophy-priced ICEpower amp in a half-empty oversized 30kg box with 2-inch face plate whose innards were no different than a €1.500 Wyred4Sound?
Kharma's original and very luxurious top monos begged to differ by incorporating Hypex technology in a special custom collaboration with Bruno Putzeys. Yet 2011's Kharma catalogue shows their new Exquisite MP1000s to be class A/AB designs again. Did ultra-priced class D amps not sell?


Introduced in Munich, Mårten Design's new M-Amp monos must hope they do. Based on Norwegian Abletec technology, the Mårtens in their lower halves however had massive linear power supplies rather than the SMPS which comes with the stock OEM modules. (Incidentally Henry Ho of H20 Audio does something similar with ICEpower by replacing their switch-mode power supply with a very beefy traditional linear sort).

Mårten describes their amps as "an inverting globally self-oscillating class D stage that's a load-independent wide-bandwidth (-3dB @ 120 kHz) 1st-order modulator which switches at 600kHz with a constant loop gain of 30dB all the way up to the switching frequency. The result is a true delay line, which displays very wide bandwidth and fast transient response. The adaptive modulation servo connects to the positive and negative inputs of the core amplifiers modulation stage to eliminate the imperfections of the modulation. The gain of the core amplifier cannot be affected by the servo.


"So the wide-bandwidth 1st-order behaviour of the class D modulator is preserved perfectly. The servo has flat 20dB gain up to 20kHz, creating constant linearity in the audio band. Two independent channels are used in a balanced configuration for a truly exceptional amplifier with a very wide bandwidth, ultra low noise/distortion, high output power and very low losses." A manufacturer whom I mentioned the M Amps to asked a question I had myself. How long could it be until a competitor issues an Abletec-based amp for pennies on the Mårten krona by doing without the the luxo packaging and monster supply? How viable is it really to turn class D into traditional—expensive, big and heavy—he-man jobs for those few who are still impressed by that?

NuForce is the only successful smaller firm with their own class D technology I'm aware of (I haven't followed what later-blooming ARC is up to on that score). Like Bel Canto, Nuforce is focused on the value segment. Their recent ascent into pricier turf occurred with their new $8.000 Reference 18 monos. This was enabled by lack of competition. Nobody else has NuForce boards. Yet eight thou remain below extreme über-amp stickers. And NuForce is the first to admit that the Reference 18s buy very small refinements over their core V3 sound; and that much of the money goes to the full-width designer chassis as the eye candy which some customers had asked for.


What thus twitched my gray matter was whether class D will ever get completely legitimized in the Boulder, Soulution & Bros. leagues. Which small hifi venture has the in-house talent (or outsource funds) to beat B&O and Philips at their own game? NuForce has shown that it's possible. The lack of from-the-ground-up competition has shown that it's rare. Now add that NuForce isn't going after the trophy hunters by claiming that with their technology $20.000 amps are even necessary. So ask the average—aspiring or arrived—audiophile for a few amp recommendations if money were no issue but performance paramount. I'd be very surprised if any class D amp got a mention. Perception in this racket is huge. I don't think class D has cracked it yet. And perhaps it's ultimately not necessary. It would after all require pandering to established high-end silliness where bigger, heavier, hotter and pricier are better.


Which begs another question. Just what will Bel Canto's über amps be like? Michael McCormick confirmed that John Stronczer is working on the answer. But I'd heard the same thing two years ago. Clearly this one is a very tough nut to crack. The only ones to really have cracked it are the folks at Devialet by inserting into their own quad-paralleled phase-staggered class D amps per channel a class A amp that provides the voltage and thus 'sets the tone' for the performance by interacting directly with the speakers. That's a very mean trick. I don't expect we'll see an encore elsewhere.


To wrap up, as is often the case with musings one doesn't always arrive at any conclusion. One circles the wagon, identifies what's in the middle, then remains undecided. That describes my thoughts on this matter perfectly. Another fine day in wonderland. At least writing it out made that itch go away...


PS: No sooner scratched, an unrelated email from Marja & Henk caused a new rash. They have confirmed word that the engineering troupe at Grimm Audio—which of course includes Bruno Putzeys—is brewing "something class D that'll be very powerful, very expensive and far superior to anything currently on the market". Ask and ye shall receive?