Grace Design M905

Reference monitor controller


This is the world’s finest stereo monitor controller, with built in mastering quality Digital to Analog
Converters, audiophile-grade headphone amplifier and unrivaled system configuration tools. For
hardworking audio professionals and studios that demand the very best playback available.
New Firmware supports Digital Speaker control via AES and S/PDIF outputs
The is our second generation stereo monitor controller, engineered from the ground up to provide
unrivaled sonic purity with a comprehensive and powerful feature set.
The m905 represents a new benchmark for audio playback quality. DAC performance is on par with the
finest esoteric mastering equipment available. Our redesigned s-Lock™ PLL ensures ultra-low jitter clock
regeneration. An asynchronous USB class 2 interface allows the m905 to act as the master clock of the
computer's USB audio buss, effectively eliminating interface induced jitter for computer audio playback.
And finally, meticulous analog circuitry measures with outstanding numbers in dynamic range, distortion
and noise performance, ensuring bracingly open, detailed and musical playback of any input source.
All main audio and power supply circuitry is housed in a 2U rack mount mainframe, while system control
is managed by a sleek, ergonomic remote control unit. This new RCU is a combination of dedicated
hardware and a color graphical LCD display. All primary monitoring features are accessed via hardware
switches and a rotary encoder, while all system information is presented by the graphic LCD and
illuminated switches. This hybrid design allows for the solid feel and function of traditional hardware
with the added power and functionality of a graphical user interface.
Now supported is DSD 128x (5.6448MHz) via DoP v1.1 (DSD over PCM frames). DSD audio can be
sourced from the AES3, S/PDIF or USB digital inputs. While still a niche playback format, DSD has held its
ground over the years, and now more and more content is available via download. And playback is now
supported by a number of players. DSD sounds stunningly natural, especially rendered through the rest

of the playback circuitry of the m905. So If you’re the type to seek out this kind of fidelity, the m905 is a
great way to enjoy it.
The GUI is designed so that any engineer unfamiliar with the m905 can use the system immediately and
confidently. Then with a minimal time investment, advanced functions can be accessed and controlled
with ease. Additional features include: naming individual inputs and speaker outputs, calibrating level
offsets of any input and output, setting preset levels, and much more. The setup menus only ever drill
down one level, so the main operating screen is always one button away. And when returning to any
previously visited setup menu, its previous edit status is remembered, keeping redundant navigation
and editing to a minimum.
The m905 offers the ability to transfer up to 10 channels of digital audio (8-channels of ADAT and two of
AES3, or S/PDIF or TOSLINK) over USB to a computer, making the m905 capable of operating as a
standalone USB audio interface. This is an advanced feature as there are clock issues to be aware of, but
it works and is documented in the owners manual.
With stunning sonic performance and timeless design, the m905 is a mark of genuine progress in the
pursuit of high quality audio production. Intuitive, reliable and beautiful, it is the perfect studio
centerpiece – home base for your ears, eyes and hands.
m905 Analog Option (analog inputs only)
The m905 Analog is now available without the built in DAC. This system is offered for users who already
have an investment in DACs, whether stand-alone or built into their interface. System configuration is
exactly the same, with all the same great monitoring features, except no digital inputs and an second
pair of balanced analog inputs. The m905 Analog brings this world class performance into reach of
almost any engineer or recording studio. Also, users can always upgrade their m905 Analog to the Digital
version at anytime. NOTE: the analog only version incudes a simplified remote cable that does not carry
headphone signal to the RCU. To enable the headphone output on the RCU, ask your dealer to upgrade
to the premium remote cable.
Phono Preamp Option
The m905 phono module is a high performance RIAA preamplifier. This option is available on new and
existing units, the latter requires the unit to be returned to our factory to be upgraded. If you are an
overseas customer, please contact your Grace Design distributor for details.
It can be optimized for a wide range of phono cartridges via a number of internal jumper settings. To
access these jumpers, remove the top cover of the m905 and refer to the Jumper Location diagrams in
chapter 18 of the Owner’s Manual.
Infrared Wireless Remote Option

Also now available is the m905 IR Remote Option, which is available on new or existing units (Digital and
Analog). This feature allows wireless infrared remote control of a select set of monitoring controls via
the Grace Design Remote, a standard Apple Remote, or with iOS and Android via the Logitec® Harmony
Analog inputs – unbalanced (standard or the optional RIAA phono input), balanced (2nd pair balanced
available on m905 Analog), CUE, talkback mic
Digital inputs – 2x AES3 (Single or dual-wire), 1 S/PDIF, 1 TOSLINK, ADAT (selectable in 4 pairs, or 2
pairs in S/MUX), USB, DSD128 (5.6448MHz)
Audio circuitry designed for completely transparent and musical playback performance
Asynchronous Class 2 USB playback supports up to 24 bit/192kHz

Mastering quality DAC circuitry with configurable de-emphasis filtering
s-lock dual-stage Phase Lock Loop for ultra low jitter clock regeneration
Hybrid RCU with hardware switches, large level encoder and graphical LCD
LCD display shows input, level, output, SPL and DAC status plus a full calibration menu
RCU includes built in microphone for talkback and onboard SPL meter
SPL meter features include level, peak, fast and slow modes, A & C weighting
Precision .5 dB step level control for speakers and headphones
Reference headphone amplifier circuitry, with outputs on both the RCU and ACU
Dedicated mono, dim, mute and sub mute switches
Digital loop thru outputs that can be configured to pass incoming digital signals or as a digital speaker
output when monitoring digital PCM sources.
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 available
3 available stereo speaker outputs, with two assignable mono sub outputs (or single stereo sub
Multi-mode SUB/ DAC/ METER out
SUB out mode for stereo or multiple mono subwoofer outputs
DAC out mode for a fixed DAC output fed by the selected digital input

METER out mode fed by selected input signal (digital or analog), configurable with a fixed level or to
follow the monitor level
Detachable RCU tilt base


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