Massdrop x Grace Design m9XX DAC/Amp

Well reviewed on Head-Fi, HiFi Insider, and beyond, the Massdrop x Grace Design m9XX was inspired by the world-class m920 DAC/amp—offering the same performance level for audiophile applications, now at a far more accessible price. Working with Michael and Eben from Grace Design, we stripped the m920 of its lesser-used pro audio hardware and improved upon the audiophile features where possible, all while retaining the high-res DAC implementation and super-clean solid-state amplification. The result? A portable, affordable, and sleek piece of gear; one that benefits from Grace Design’s decades of expertise in analog circuitry and better serves the needs of the audiophile community.

The digital section of the m9XX utilizes a top-of-the-line AKM chip. Part of the newest generation of converters from AKM, the AK4490 features 256x oversampling, 32-bit processing, and sample rate compatibility from 44.1 kHz all the way to DSD128. The m9XX even offers a variety of anti-aliasing filters to choose from, something that is rarely included in this price range or physical size. The digital USB controller is an eight-core XMOS processor that operates in asynchronous mode and is immune to USB buss jitter, which can adversely affect sound quality in the transfer. The m9XX is also capable of receiving a digital signal up to 96 kHz/24 bit via Toslink.

The Grace m9XX has a direct-coupled design with no capacitors in the signal path and the output amplifier is DC servo-controlled, ensuring zero phase shift for the ultimate in clarity and resolution. High-quality resistors in the circuit path help the m9XX deliver a low-noise, low-distortion signal, along with dynamic accuracy and excellent channel matching to the headphones. The amplifier section is built around the TI THS6012 current feedback chipset, but has been modified with a proprietary circuit topology to zero output impedance for a maximized damping factor, even with sensitive IEMs. This allows the m9XX to deliver all of the ultra-high resolution and clarity of a current feedback amp with all of the control and dynamics of a zero-output impedance headphone amplifier. The compact m9XX even includes new crossfeed circuitry that sonically distributes the stereo image across your headphones’ soundstage, helping to reduce listening fatigue over time. Toggle this on or off from the device menu.

The power supply design of the m9XX is unique. In total, there are five separate power supplies at work delivering clean, isolated power to the digital and headphone amplification sections. The back panel features two micro-B USB connectors, one for connecting to a wall charger and the other for connecting to a USB source. The m9XX can independently operate from its USB bus supply up to 100 mW of power into a 32-ohm load (per channel with two channels driven). Plug the device into the wall for additional amplification power up to 1,000 mW into 32 ohms (per channel with two channels driven). The power supply in this compact device is carefully filtered, with multi-tiered noise suppression for artifact-free playback from the sensitive DAC circuits and amplification unrestricted by any annoying buzz or background hiss. All that’s left is your music ripe with dynamic response, crystal-clear detail, and musicality unheard of in this price range.

Jude’s First Impressions

Head-Fi

HiFi Insider