Grace Design m903 Reference Headphone Amplifier, DAC, and Monitor Controller

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.