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

B&H # GRM903 Mfr # A903
In Stock: Shipping Only
Free Expedited Shipping
You Pay: $1,595.00
Product Highlights
  • Audiophile-Quality Sound
  • Compact Design
  • 24-bit/192kHz DAC
  • Multiple Analog and Digital Inputs
  • USB Interface

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
Number of Channels 2
Input Connectors 1 x Balanced XLR Analog Input (2 Jacks, L/R)
1 x Unbalanced RCA Analog Input (2 Jacks, L/R)
1 x XLR AES Digital Input
1 x Optical TOSLINK Digital Input
1 x RCA S/PDIF Digital Input
1 x USB Digital Input
1 x Power Input
Output Connectors 2 x 1/4" Headphone Outputs (Front Panel)
1 x Stereo 1/4" Balanced Line Output (2 Jacks, L/R)
1 x Stereo RCA Unbalanced Line Output (2 Jacks, L/R)
Maximum Input Level +22dBu, Balanced and Unbalanced
Maximum Output Level +22.5dBu, Unbalanced
+27dBu, Balanced
+20.4dBu, Headphone
Gain +15dB, Headphone Output
+14dB, Balanced Line Out
+11dB, Unbalanced Line Out
Frequency Response 4Hz - 600kHz @ 0dBu Out ±3dB
Impedance 106 kOhms, Balanced In
53 kOhms, Unbalanced In
95 Ohms, Balanced Out
47.5 Ohms, Unbalanced Out
1.2 Ohms, Headphone Out
THD + N <0.01% (+10dBu Out, 50 Ohm Load, SMPTE 4:1)
<0.008% (Headphone +10dBu Out, 50 Ohm Load)
<0.02% (Line Out +10dBu Out)
Input Attenuator < 0.05dB Channel Matching
99.5dB Range
Function Controls 1 x Power Button
1 x Level Control
1 x Input Select Control
Dimensions (WxDxH) 8.5 x 8.25 x 1.7" (216 x 210 x 43mm)
Weight 5 lbs (2.2kg)
Grace Design m903 Reference Headphone Amplifier, DAC, and Monitor Controller
  • Power Cord
  • 5-Year Transferable Parts and Labor Warranty
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