Refined and Rich Sounding
Ten years ago, Grace Design launched the model 901 headphone amplifier and followed it four years later with the popular m902. How could Grace possibly top the m902? The company's new m903 is a refined and rich-sounding headphone amp with an onboard 24-bit, 192 kHz DAC. A full complement of connections adds to the impressive features list.
"The Grace Design m903 continues the tradition set by its predecessors by being 'a great, high-resolution DAC on a very cost-effective package' that offers remarkable clarity, continuity, and roundness of tone, and is better in almost every way than the m902," notes John Marks in the December 2011 issue of Stereophile magazine.
New Design Ups the Ante
The Grace m903 retains everything that was great about its predecessors, adds some useful new features, and ups the ante with even better audio performance. A new volume control provides higher headroom and lower distortion and noise. New generation DACs and an ultra-low noise, balanced current-to-voltage converter yield even more musical performance compared to the m902. The improved s-lock PLL circuitry delivers lower phase noise and jitter. An improved power supply isolates headphone amplifiers, line amplifiers, DACs, and digital logic, resulting in lower noise and distortion.
All New-High Speed USB Interface
Perhaps the most exciting improvement is the all new high speed USB interface. This cutting edge technology provides a completely asynchronous data transfer mode, which allows for bit-perfect USB playback with zero interface-induced jitter. This new interface affords standard driverless USB 'Class 1' operation on Windows and Mac up to 24-bit, 96 kHz and USB 'Class 2' audio for 24-bit, 192 kHz operation on Windows and Mac (drivers are needed for 192 kHz operation under Windows). This is computer-based audiophile playback that will satisfy the most diehard purist.
New crossfeed circuitry is even more useful and includes a gentle compensation to eliminate the perceived loss of low frequency content. Both balanced and unbalanced line outputs are now standard, with individual volume controls for each. Grace Design has even included a mono mode for checking a mix for phase issues or simply monitoring in mono (or listening to Pet Sounds). These improvements cement the m903 as the perfect compact, audiophile-grade monitor controller, even for larger scale production environments with more than one set on monitors.
A Full Complement of Connections
Oodles of connectivity extend the capability of this superb component. A full complement of analog and digital inputs are provided: balanced, unbalanced, AES3, S/PDIF, Toslink, and USB. They are user-selectable via a precision rotary front panel switch. Grace also offers an updated optional infrared remote control, which provides essential control for anyone working 'out of reach' of the m903. | 
