Grace Design m905 Reference Monitor Controller: Stereo Unit With LCD Display, Remote and USB Interface

When I first began making records, I quickly came to the understanding that everything in the signal path contributed to the quality of my system’s output. In the recording and mixing process, I wo

When I first began making records, I quickly came to the understanding that everything in the signal path contributed to the quality of my system’s output. In the recording and mixing process, I would typically listen through the monitoring section of a console, but when attending mastering sessions, I began to notice these studios had unique monitoring controllers that allowed them to interface different sets of speakers, clocks, converters, CD players and more. When DAW recording became more popular, many of my peers and the studios I worked in became more reliant on the same types of interfaces.

Cutting down on the amount of physical circuitry that the signal had to travel through to get to the speakers seemed ideal, and I replaced my own monitor path with a dedicated controller as well. I immediately noticed a stunning difference in audio quality, detail and clarity in my recordings and reference materials. I was very familiar with Grace Design and the original m906 surround controller, which I had used during mixing for a live DVD that I had recorded. Hearing that the company was introducing a new stereo version—the m905 Reference Monitor Controller—I wanted a listen.

Gracefully Executed

The box came with three boxes inside, one housing the two-rackspace unit, and two more boxes containing the LCD remote, manual and cabling. The main unit (ACU) is well-built and weighs in at just less than 8 pounds, while the remote comes in at just more than 2 pounds. The DB15 pin serial cable is long enough to accommodate most control room spaces, and the communication port on the main frame will allow for a future wireless adapter.

The m905 offers the ability to transfer up to 10 channels of digital audio (eight channels of ADAT at 44.1 and 48k, four channels at 88.2 and 96k, and two of AES3, or S/PDIF or TOSLINK) over USB to a computer, making the m905 capable of operating as a stand-alone USB audio interface. This is an advanced feature, as there are clock issues to be aware of, but it works well and is documented in the manual.

The digital channels are all sourced through a same D/A circuit, so your comparisons are matched. There is even DSD audio support through the AES3 word clock I/O. The built-in 60-watt power supply is connected via a standard IEC cable. The analog inputs are balanced and unbalanced, and include a cue stereo out that sums the cue input signal with the talkback mic signal. Also offered is a Grace Design preamp/external talkback with switchable phantom power and 70 dB of headroom. The talkback mic on the remote doubles as a calibration mic that continually measures the SPLs in dB level in the studio, a feature I found to be very useful over long workdays. There are three available speaker outputs, and two assignable mono sub outputs or single stereo sub outputs. The internal clock that accompanies the m905 is phase-locked for ultra-low jitter regeneration.

Flexible Control

The hybrid remote (RCU) features hardware switches, a large level encoder and a graphical LCD display that shows input, level, output, SPL and DAC status, plus a full calibration menu. It has a detachable tilt base that allows the user to customize the viewing position. The onboard SPL meter features include level, peak, A and C weighting, and fast and slow modes. The m905 features reference-headphone amplifier circuitry, with outputs on both the RCU and ACU, and includes precise 0.5dB step-level control for speakers and headphones with saveable presets. There are dedicated mono, dim, mute and sub mute switches, and mono mode can be set to L+R summed, L only in both channels, or R only in both channels. L solo, R solo, L-R and sub solo modes are also available. Three stereo speaker outputs are available on the m905, with two assignable mono sub outputs (or a single stereo sub output). There are Multi-modes on the m905, Sub out mode for stereo or multiple mono subwoofer outputs, DAC out mode for a fixed DAC output fed by the selected digital input, and meter out mode on the m905 is fed by selected input signal (digital or analog), configurable with a fixed level or to follow the monitor level for calibrating mixes to reference material.

Grace has spent a considerable amount of time to make the unit as plug-and-play as possible. I easily connected to a Mac laptop by way of the USB 2 I/O. Then I opened Pro Tools and the m905 recognized the DAW immediately. (I did not have a Windows-based machine, but understand that the USB 2 driver available on the Grace Website will allow for the same control once the computer is pointed toward the Grace audio device. There is no current support for Windows 8.) Grace uses an asynchronous mode in the USB converter to create a significant improvement over any other previous type of USB DAC. In this mode, the m905’s crystal-based clock becomes the master to which the USB bus is synched—the system works with zero interface-induced jitter and perfect bit playback.

There are many advanced features on the stylish, well-lit LCD remote that can be modified to suit individual needs. Renaming inputs and outputs, calibrating offsets between sources, and setting preset levels are just a few features at your control on the RCU. The setup menus on the soft buttons only step down one level, so the main display screen is only one touch away. The large rotary volume control travels in weighted increments of -.05 dB, yet there are no relays ticking away as they do on my Dangerous Monitor ST. Pressing the dial inward switches between the output level of the speakers and the headphone control, which for the first couple of days took some getting used to, but I grew to like the quick access. The ¼-inch TRS connection on the back of the remote was handy for bouncing between my PMC TB2 monitors and a pair of Audio-Technica M50 headphones. Checking cue sends to my rooms was also one click away, as were the different sets of speaker outputs, mono and mute, setup, and talkback buttons. The constant SPL metering on the remote was a feature I really grew to love, and my ears were certainly thankful.


I hit the power button on the ACU and the illuminated display on the RCU came to life. It is visually stunning upon first glance: The display is easy to read and the interface is very intuitive. I found myself scrolling through the sub-menus quickly and referring to the readouts for accuracy. After scanning the manual, I was able to create presets to identify the gear connections and also double-check the digital sync. The factory settings were very finely tuned and found the main sets of I/O needed for calibration in my studio. I fine-tuned the output of my Mac Pro tower to match the output of AES and my UA2192, and began listening to some reference recordings and mixes.

The m905 was sonically transparent and detailed in every frequency range. When turning up the volume, the unit stayed as true as at low levels, even when auditioning the dim switch. Not hearing the stepped clicks of my own familiar DAC took a bit of getting used to, but seeing the SPL levels allowed me to increasingly rely on the RCU. I thought it would be nice to see a loudness meter—maybe it will show up in a future software update.

Next, I removed my own converters and listened completely through the m905. Again, very clear, present and balanced sonics throughout every source I auditioned. The conversion inside the m905 is certainly mastering-quality.

Finally, I connected the m905 to my MacBook Air via the standard USB 2 port. The computer recognized the unit on my first try and within minutes I was hearing audio. I could easily toss this in a rack and use it on single instrument or vocal overdubs. It provided great conversion, a reliable and clean headphone amp, full connectivity, and a great high-gain/low noise floor preamp.

Reliable Source

I’m a firm believer in creating the shortest signal path from an audio source, and having a great DAC has surely become one of the most important parts of my studio. It keeps me from making corrective decisions with EQ, and from hearing phantom artifacts. The Grace Design team left no stone unturned in developing their latest DAC version, and it would equally be at home in a high-end project studio, top-level commercial and mastering facilities, and even an audiophile’s favorite listening room. The setup and design is of the highest quality, and is easy to integrate into any studio setup very quickly, so you’re not spending time paging through manuals; you’re spending more time listening to how great your recordings will sound.

Chris Grainger is a producer/mixer/engineer and owner of Undertow Studio in Nashville. Visit his Website,, or follow him on @itsgrainger.


Connect a computer tower or CD output via a Toslink connection and pull up one of your favorite reference tracks. Use the RMC’s talkback mic to calibrate the digital output levels to match your DAW output for seamless comparison.

Product Summary

COMPANY: Grace Design

PRODUCT: m905 Reference Monitor Controller


PRICE: $3,325

PROS: USB DAC driverless interface for Mac and Windows devices. Mastering reference quality speaker and headphone outputs. Built-in talkback mic and Grace pre that continually measures SPL via the remote.

CONS: USB connection via the upgrade port caused a communication error freezing the remote. Would like to have a loudness meter on the RCU.

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