Grace Design: M908 Monitor Controller

Grace Design has been making some of the most respected preamps and monitor controllers for nearly 30 years (and since has branched out into acoustic instrument preamps and processors). Their latest flagship monitor controller, the m908, is a multi-channel beast that goes far beyond the stereo capabilities of the m905 [Tape Op #97], with simultaneous control of up to 24 possible speaker channels. It’s designed to be a one-size-fits-all monitor controller for everything from stereo, to 9.1.6 Atmos, to a 22.2 experimental installation configuration, and all possible formats in between. The m908 system’s brain consists of a rack-mount ACU (Audio Control Unit), which includes all of the I/O, and a sizable external dual-redundancy power supply. An RCU (Remote Control Unit) is used for accessing and programming the ACU parameters. This unit sits on your desk and serves as the interface for anything monitoring-related that one could think of.

The ACU comes standardly equipped with 24-channels of AES digital I/O, 16 channels of ADAT Lightpipe I/O, 24 channels of input and output over USB, 16 channels of analog output, and AES, coaxial S/PDIF and optical TOSLINK stereo digital inputs. Grace also offers optional ADC1 analog input modules in 8-channel cards (which, if added, can include an additional analog stereo input via XLR, and an optional phono input via RCA), plus Dante, and Avid DigiLink cards for integration into existing systems. The ACU can sync via word clock to other converters, or be the clock master. Grace’s own converters and clocking sound astonishing, and I would rate them against any currently available AD/DA converter. They can operate up to 192 kHz. Both the RCU and ACU have incredible-sounding headphone amps with an optional cross-feed function that simulates listening on speakers while listening with headphones.

Not content to be “just” the volume control in your studio, the RCU can quickly become as pivotal a piece of gear in your studio as your DAW. The LCD display provides a wealth of information on the main page such as current speaker configuration (with levels displayed as green/yellow/red on each speaker icon), volume setting of the monitors and headphones, sample rate, clock source, current and maximum measured decibel level via the built-in talkback mic, and (finally) eight of the possible 16 preset input sources. From the RCU, we can also access full speaker calibration settings including up to 12 bands of EQ per channel, delay in milliseconds per speaker, and bass management for the entire configuration. Programmable buttons on the RCU can be assigned to handy functions, such as bypassing bass management, or folding down from 7.1.4 to 5.1. The mono button becomes a Left minus Right monitor when activated by a long press – an excellent tool for quickly finding polarity issues or determining if that “stereo” track is actually just the same thing on both sides.

Multiple input sources can be active and summed with a programmable offset between sources. This can be handy if you are using USB for system audio on your computer and want to reference playback from YouTube or Apple Music while also monitoring the output of your DAW via AES. In addition, there are three Control Room setups, each with a dedicated button on the remote for switching between speaker configurations.

These specs and features may look amazing on paper, but can only be properly judged in practice. I’ve been using the m908 in my Atmos mixing room, and it has been invaluable in every way – sonics, programmability, flexibility, and more. I asked for the review unit to be equipped with a DigiLink card, plus two analog input cards. I used the DigiLink input for the first couple of months until I sold my HDX card and moved to a Thunderbolt 3-based converter. At that point, I moved the inputs to the analog cards and no longer needed to clock the m908 to my converters – it has been set to its own clock at 96 kHz since that time. The ability to adjust for level and delay on a per-speaker basis is a massive part of calibrating an Atmos space, and the m908 handles this easily. Delays are adjustable by 0.1 milliseconds, and levels in 0.5 decibel increments. This power in the monitor controller means not having to rely on the Dolby Atmos Renderer for proper calibration. Additionally, having these settings available when working in any other format (stereo, 5.1) removes the Renderer from the monitoring experience.

The volume encoder on the RCU is also a switch used to enter/confirm parameter changes, can alternate between the speakers and headphone volume, and can be programmed to mute the speakers when switching to headphones – handy when tracking vocals in the same room! You can also mute or solo any output, so checking height channels on their own, or muting the sub/LFE can be achieved at the press of a button. The ability to perform all these actions throughout the day, almost unconsciously, is beyond handy.

Near the end of my review period, Eben Grace and Alex Vallejo from Grace Design support sent over a beta of their latest firmware update, which should be available publicly by the time this review is printed. Updating the firmware for the m908 is as simple as copying the file to a USB stick formatted for the Grace, then running the ACU and RCU updates with a power cycle at the end of the process. The most significant feature of the new firmware is the ability to control the m908 from a web browser, which also requires creating a network between the ACU and your computer with an Ethernet cable. Once that is complete, logging into the m908 via the browser allows access to all parameters and programming, making editing and changing settings much faster than diving through the pages on the RCU, particularly when naming configurations. This allows the RCU to do what it does best, and the computer to lend a hand for data entry – very slick!

I find a monitor controller to be an indispensable part of day-to-day studio life, particularly in a console-less room without a master section for speaker/input switching. Now, with multi-channel mixing schemas like Atmos becoming more prevalent, a properly-built monitor controller for that scenario is vital. The Grace Design m908 absolutely fits that description – incredible sound quality, options for almost any input and output need, and the flexibility to program multiple speaker layouts and have them available at the press of a button are just a few of the standouts in this truly full-featured unit. If there were anything I would ask for as an addition to the programmable functions, it would be functionality for adjusting the polarity/phase rotation per speaker, especially for the LFE/subwoofer output. Other than that, I really don’t have any bones to pick with the m908. It’s a brilliantly-engineered piece of work, the RCU is an incredible interface into the inner workings of the ACU, and it looks like a piece of art on your desk.

Nothing this powerful can be made cheaply, so it’s not an inexpensive investment, but when adding together all of the components and the number of channels that are under the control of the m908, it really is a bargain. If you currently have an Atmos-equipped room or are thinking about expanding in the future, this is the unit to put at the top of the list. Even if you don’t want to move in the direction of Atmos, 7.1.4 or 5.1, this would still be the ultimate monitor controller for a stereo room, too.