Even though class D amplifiers are usually light in weight, generate very low heat and operate very efficient, over the last decade we have seen many related improvements from manufacturers trying to raise quality standards. Take Mola Mola for example. When still working at Hypex—he is now busy at Kii and Purify—Bruno Putzeys fathered nCore with the model 1200 as the top dog. When he founded his Mola Mola brand, he took the already high-quality NC1200 module to an even higher level. Next to even narrower parts tolerances, he mounted the circuit board into a heavy inert solid aluminum housing. And instead of a switching power supply common to most D class amplifiers, he went for a big linear version. These improvements especially in the casing and power supply are now seen with many high-end class D efforts. The heavy casing works twofold. It prevents self-generated EMI radiation from getting into nearby equipment and blocks external vibrations from getting access to its own circuitry.

What is the solution which SPEC introduced to overcome the vulnerabilities of their high-efficiency platform? First they turned to solid wood. The chassis of both power supplies and amplifiers are made from different types of wood, notably tone woods. Here the designers looked at musical instruments and the various wood types they exploit. Maple, hickory and spruce in either solid or laminations make up the side and bottom panels, corner staves and three footers. But wood has another characteristic next to vibration control. It can absorb EMI/RFI radiation. Other companies exploit this too like PS Audio with their piano-gloss wooden top plates of the PerfectWave models.

Our four 45 x 18 x 44cm loaners found spots between our Avantgarde Duo Omega hornspeakers. We placed the power supplies left and right from their power amplifier mates reSPECtively. The back of the power supplies offers a mains switch above the IEC power inlet with a separate fuse next to it. A three-way slider controls the light indicators of both the power supply and connected amplifier. One can choose a white strip across the full width of the frontal indicator or a dimmed version for just the center part using a warmish yellow color. Then come two (!) DC outlets where umbilicals forward DC power to the amplifier. One outlet is labeled sub, the other main.

It is a bit busier at the rear of the power amplifier. We've said power amplifier already a few times but we will see that this nomination is a bit misleading. At the far left we get the DC inputs for the sub and main leads. Above that sits a sound mode selector labeled 1 for 'neutral' and 2 for 'sophisticated'. A three-way slider labeled 'gain' includes a max setting by expecting a preamp to do volume. Selecting the -6dB option lowers the amplifier's output by 75%. SPEC-VOL is the setting when the external SPEC attenuator called H-VC5 is used. We found this switch easily prone to slide to an unwanted setting with all the associated risks for the attached loudspeakers. When we mentioned this to Banno-san, he confirmed that they were already considering an alternative.