Reviewer: Joël Chevassus
Financial interests: click here
Source: Esoteric K-03, Lumin S1, Apple iMac Lion/Audirvana, Trends UD-10.1, MacBook Lion with HiFace USB bridge
Amp/Preamp: Coincident Technology Statement Line preamplifier, SPL Volume2, Luxman M-800a x 2 (bridged), Trends TA-10.2, Ristea tube preamplifier [on loan]
Speakers: Vivid  Audio Giya G1
Cables: Skywire Audio 2020 digital cable, Naturelle Audio interconnects Live 8 MK2, Grimm Audio TPM interconnects, High Fidelity CT1 Enhanced speakers, DIY NOS copper speaker wires
Power cords: DIY, Triode Wire Labs 10+
Stands & room: Music Tools Alicia furniture, DAAD 4 bass traps, Microsorber room insulation, PYT panels
Review components retail: $1,999/ea.
Is there a future still for painfully inefficient fire-breathing music machines? A decade ago, state of the art solid-state amplification was based on pure class A behemoths with enormous power transformers and frightening heat sinks. Famous designers like Antony Michaelson of Musical Fidelity even proposed that sound quality was closely linked to very low efficiency not exceeding 5%. Luxman Corporation celebrated their 80th anniversary with very sophisticated class A amplifiers and state of the art PCBs whilst Hans Ole Vitus was paving new cornerstones in class A amplification. Also at that time, class D switching amplifiers began being actively promoted by a few manufacturers like NuForce, Bel Canto, Rotel and Flying Mole, most of them relying closely on B&O's early IcePower modules. Then Hypex came to market with interesting OEM alternatives. Today we have newer comers like Patrik Bostrom of Abletec/Anaview (Sweden) and Jesper Hansen of Pascal (Denmark) who extend the market of ultra-efficient class D building blocks in the wake of Bruno Putzeys whose modified Ncore output stages I reported on in my review of Bel Canto Black. Each of these more recent players have their own control mechanism, output filter and control loop which will influence how the amplifier will sound and interact with a loudspeaker load.

In fact, class D technology keeps pushing forward with ever more efficient designs. At Abletec, new phase-shifting modulation represents a significant improvement over older pulse-width modulation which has been common to switching amps for many years. Their Adaptive Pole Control (APC) and Adaptive Modulation Servo (AMS) are proprietary circuits that strive to optimize the behaviour of basic globally self-modulated class D topologies without increasing the parts count. The Danes at Pascal have been in business since 2006, just shy of 10 years. They also introduced a new wrinkle on the concept called UMAC class D, a patented design which uses an advanced control circuit for full bandwidth output. Pascal also tout the power factor correction of their power supply and universal regulated error-correction technology. So where does that put us today and tomorrow?

Dan D'Agostino's recent audio jewelry business seems to demonstrate that room remains for heavy hitters in the high-end audio market. Karan, Pass and Vitus continue with imposing steel beasts of ground-breaking class A performance. Japanese brands Luxman and Accuphase continue with similar topologies. If we look closer, most nevertheless remain in a reasonable power range. The old Krell monsters capable of a kilowatt or more have quite disappeared from our landscape. And only a few of today’s class D productions step into the fray to feed those most ambitious of low-impedance power requirements. They are then always accompanied by that secret worry. Are they really fully stable into such loads? In other words, does there remain a material difference between 'small watts' and 'genuine watts' as old-fashioned manufacturers might claim? In my view, that’s a really interesting question and one I shall endeavour to answer.