The Grace Design m920 marks the latest release in Grace's ledgendary headphone amp/monitor controller line. At the heart of the m920 is the latest generation M series Sabre DAC. The Sabre is a 32-bit converter that takes DAC performance to an entirely new level. 24-bit, 192 kHz inputs are provided on AES3, S/PDIF, TOSLINK, and asynchronous USB. The m 920 includes DSD-64 and DSD-128 functionality via USB, DSD-64 through the AES3 or S/PDIF inputs, and 352.8 kHz and 384 kHz PCM (DXD) playback over USB. User selectable DAC filter response is available for both PCM and DSD playback. Grace has improved the performance of its s-Lock PLL for increased jitter rejection, and the ability to disable this if not needed for a particular application. A new cross-feed circuit has been developed for improved headphone imaging, and low frequency response has been improved on the balanced and unbalanced line outputs.
- new, world-class M Series 32-bit Sabre DAC (it’s incredible)
- 24-bit/192kHz PCM via AES3, S/PDIF, TOSLINK and asynchronous USB
- DSD-64 and DSD-128 over asynchronous USB
- DSD-64 via the AES3 and S/PDIF inputs
- 352.8 and 384 kHz PCM (DXD) over asynchronous USB
- Brand new cross-feed algorithm for even greater headphone imaging
- Frequency Response: 4Hz-192kHz
- Output Impedance 1.2 ohms
- Dynamic Range: 117dB
- THD+N: less than 0.0005%
- Dimensions: H1.7" x W8.5" x D8.25"
- 1/4 inch headphone connectivity
- Weight: 5 pounds
- Manufacturer Warranty: 5 years
What's In The Box:
- Grace Design m920 Reference Headphone Amplifier and Monitor Controller
- IEC Power Cable
- Removeable feet
- Extra Power Input Fuse
- Owner's Manual
The m920’s audio circuitry and power supply is housed in an elegant 1U, half-rack enclosure. The front panel includes a pair of 1/4” TRS headphone outputs, and an LED display for headphone and line level output levels. Level control, adjustable in .5 dB increments, is accessed via a multi-purpose rotary encoder/switch, that also serves as an output selector, and a setup menu navigation tool for selecting and adjusting m920 operating modes and parameters. For users who would like to use the m920 as a dedicated DAC, a mode is available that allows the level control encoder to be bypassed, which feeds the unbalanced line level outputs. A second rotary switch provides input selection. A full compliment of LED's are provided for clear visual indication of outputs currently selected, and other system states such as sample rate, s-Lock, DSD, and cross-feed.The rear panel provides access to a pair of balanced analog inputs on XLR's, and unbalanced analog inputs on RCA jacks. Balanced line out's are on 1/4” TRS jacks and unbalanced line outputs are available on RCA's. Digital inputs to the m920 include AES3, S/PDIF, TOSLINK, and a Class 2 asynchronous USB port.Commenting on the release of the new m920, VP of Sales and Marketing, Doug Wood notes “The m920 is the result of feedback we've had from m903 users for a product that retained a similar look and feel, ease of use and long-term reliability, with the addition of high sample rate DSD and DXD functionality.
The asynchronous mode USB converter in the m920 represents a significant improvement over any previous type of USB DAC. Previously, a USB DAC worked under standard adaptive mode USB audio, which means the DAC’s clock would have to sync to the non-audio related computer USB buss master clock. As you can imagine, the computer has a lot else to do, so the incoming clock signal to which the DAC’s clock would have to sync was not ideal and would result in unwanted jitter.
With asynchronous mode USB, the USB DAC becomes the master to which the computer’s USB buss gets synced. So the computer is now synced to a crystal-based audio clock signal and the system works with dramatically lower jitter. No phase-lock loop or sample rate conversion is necessary, which means bit-perfect playback from a computer with zero interface induced jitter. In addition, the USB port ground is completely isolated from the m920 audio ground. This eliminates the possibility of noisy computer grounds inducing any noise or impurity in the m920 audio circuits.
Computer Audio Requirements
Regardless of the type of computer you will use to playback audio from, it must have at least one available USB port. The m920 ships with a standard USB type A to type B mini cable. The type A connector plugs in to the computer and the type B mini connector to the USB m920 input.
The m920’s asynchronous mode USB DAC supports standard driverless operation on MAC to 384kHz and on PC to 96kHz. For sampling rates above 96kHz, PC users will need to download and install a free driver on their computer, found here - Windows USB Audio Class 2 Driver v2.19.0
Driverless operation basically means ‘plug and play’. The m920 will automatically show up in your computer’s list of supported audio devices as ‘Grace Audio Device’. In most cases, simply choose that as your audio playback device and the system will work. Different operating systems and audio players will pose their own set of complications in setting up the m920 as the audio playback device. In the event that ‘plug and play’ operation does not occur, you will need to look at some specific setup variables for your player and OS. In this case, we will direct you to a very well written and comprehensive document by our friend and colleague Charles Hanson from Ayre Acoustics. Check out the link HERE. This is an invaluable resource for computer/USB audio setup information for most current operating systems, and we strongly urge you to familiarize yourself with the information pertaining to your specific OS.