The m903 from Grace Design is a stereo reference headphone amp and monitoring controller designed to provide audio professionals with exceptional headphone and stereo mains monitoring, whether from an analog or digital stereo source. Housed in a sleek 1U half-rack enclosure, the m903 offers a wide variety of analog and digital input connectors for critical monitoring of virtually any audio source.
Each of the digital stereo inputs features a 24-bit/192kHz capability. The internal DAC uses Grace's s-Lock PLL for very low jitter and incredibly solid digital performance. The high-current amplifier circuitry is designed to drive headphones with a variety of impedances with ease. A high-speed USB interface with a completely asynchronous transfer mode allows bit-perfect playback with zero interface-induced jitter. The USB interface supports driverless operation on Mac and Windows at rates up to 24-bit/96kHz, and up to 24-bit/192kHz with drivers.
The front panel of the unit offers easy to use input selection and volume level controls. The level control offers a 99.5dB range with 0.5dB steps. Channel matching is provided with an accuracy of 0.05dB. Only the highest-quality metal film resistors are used throughout the amplifier, and there are no electrolytic capacitors in the signal path. Sealed gold contact relays are used for all signal switching, and the internal linear power supply features a custom wound toroidal transformer so you get nothing but the highest quality and performance from all aspects of your amplifier.
- Compact and lightweight construction, ideal for use in studios or on the road
- Balanced and unbalanced XLR and RCA analog inputs, plus RCA and 1/4" outputs with level control
- Digital stereo inputs include AES2, S/PDIF, TOSLINK, and USB, supporting rates up to 24-bit/192kHz
- High speed USB interface has a completely asynchronous transfer mode that allows for bit-perfect playback with zero interface-induced jitter. It supports the USB Class 2 audio specification for driverless operation on Windows and Mac up to 96kHz/24bit, and up to 24-bit/192kHz with drivers
- New generation DACs and an ultra low noise balanced current to voltage converter yields more musical performance compared to previous models
- Mono mode lets you check for mix phase issues
- s-Lock phase lock loop sample clock regeneration delivers ultra-low jitter and rock solid digital stability
- High-current transimpedance headphone amplifier circuitry can effortlessly drive low impedance headphones
- Improved power supply architecture isolates headphone power amplifiers, line amplifiers, DACs, and digital logic
- A precision level control provides a 99.5dB range in 0.5 dB steps, and a channel level matching accuracy of 0.05dB
- An improved x-feed circuit eliminates the perceived loss of low frequency content
- Internal linear power supply with custom wound toroidal transformer
- Sealed gold contact relays used for all signal switching
- Optional IR remote available separately for wireless control