More than one audiophile, upon spotting the M-150 for the first time and noting its modest dimensions, assumed it was a Class D amplifier. It isn’t—this product operates in AB. What the M-One integrateds have that allow for their form factor and an AB topology are LLC resonant power supplies, a subclass of the switch-mode power supply (SMPS) that is common in Class D amplifiers, but one that generates less EMI. The greater efficiency of the switching supply is seen—the power supply is considerably smaller and lighter than the toroidal transformer(s) of a traditional linear PS producing an equivalent amount of power. The Class AB output stage avoids the nonlinearities of Class D operation, including increased total harmonic distortion and intermodulation distortion. A significant amount of heat does need to be dissipated and, without large external heat fins or perforations of the unit’s top surface, this design challenge is handled elegantly in the M-One series amplifiers. An aluminum forced convection cooling “tunnel”—coupled thermally to the enclosure—runs from one side of the amp to the other, warm air coaxed to the laterally placed vents by an ultra-quiet fan that turns on when needed. The top of the unit feels quite warm to the touch when the M-150 has been running a while. That’s a good thing: Heat is making it to the outside world and temperatures inside the M-150 remain optimal for electronic function and semiconductor longevity.
The M-150’s DAC is the well-regarded AK4490EQ, a 32-bit device that supports up to 768kHz PCM and 11.2MHz DSD digital inputs. Micromega decided to pass on licensing full MQA decoding. From the DAC onward, the signal path in the M-150 is fully balanced, converting to single-ended just before the amplification stages. For those connecting the component to an external power amplifier, the signal remains balanced all the way to the XLR line-level outputs.
The M-series integrated amplifiers feature Micromega’s own DSP room-correction software, known as M.A.R.S. (Micromega Acoustic Room Correction). A high-quality calibrated microphone is supplied and the process addresses both frequency response and phase/timing aberrations caused by system/room factors. Micromega’s design team decided to keep the application easy to use: Only three microphone positions are required and correction is limited to the bass. According to Adrien Hamdi, Micromega’s Sales & Marketing Director who was in the U.S. to attend RMAF, the feeling at the company is that electronic manipulations higher up in the frequency spectrum would change the sonic signature of the system. There’s no adjustability at all to the range of frequencies that M.A.R.S. can be applied to, something I’ve found to be advantageous with the Anthem Room Correction software I’ve used for years, and one cannot view the before-and-after response curves. But the application does work, with better bass clarity and top-to-bottom focus after a calibration has been performed.
The well-designed remote control—a device with pleasing heft, but not usable as a murder weapon like some high-end remotes—allows the user to turn on the amplifier, select sources, change the display, and adjust volume, but full functionality of the M-150 comes with downloading the Micromega app onto an iOS or Android smartphone or tablet. In addition to replicating most of the remote’s functions, one can rename inputs and adjust balance, maximum volume limit, and sensitivity. With the M-150 connected with an Ethernet cable to a network, a user can visit the vast universe of Internet radio and has facilitated access to Tidal, with Qobuz to follow in the near future. One can connect to music stored on a server or NAS.
The Micromega M-150 was in and out of my audio system over the course of more than two months. In addition to auditioning the product in an analytical mode, I used it for reviewing recordings and for casual listening. In all of these contexts, the M-150 was a welcome companion, whether it was driving the T+A Talis 300 loudspeakers, the Marco Serri Design Shoebox/Boot satellite/subwoofer system, or my reference Magico S3 Mk2s. Using the various digital inputs, the amp revealed itself to have both refinement and, when required, sufficient muscle for a wide range of music. The M-150 delivered the high-octane drive of the opening cut on Lyle Lovett and His Large Band while at the same time resolving subtle details of the arrangement. Just as impressive was the Micromega’s correct scaling of each of the Danish String Quartet’s four instruments on the ensemble’s recent ECM New Series release programming Bach, Shostakovich, and Beethoven.
The excellent performance of the phonostage was an unexpected bonus. One could be excused for assuming that, in a component as versatile in the digital domain as the M-150, the inclusion of a phonostage might have been an afterthought. Not so, not by a long shot. Playing records on my modest analog rig—a VPI Scoutmaster with JMW Memorial tonearm and Sumiko Blue Point Special Evo III cartridge—with the input impedance set at 47k ohms, the noise floor was gratifyingly low, even with ten-foot interconnects from turntable to Micromega. With orchestral music, massed strings were silky smooth and woodwind timbres were beautifully characterized. There were plenty of the detail and nuanced dynamics associated with good vinyl playback.