Grace M900 Portable DAC Headphone Amplifier

Tiny Box, Huge Sound

The m900 is a portable, desktop friendly headphone amplifier / DAC / preamp combo designed to give audio professionals and enthusiasts musical and transparent audio playback from USB, S/PDIF or TOSLINK sources. For small DAW studio setups, portable laptop editing or mixing rigs, or just pure playback enjoyment, the m900 provides the same analog and DAC quality as our large monitor controllers, but in a small, rugged and surprisingly affordable unit.

Incredible DAC Performance

The m900 DAC uses the latest generation AKM 4490 chip, which features 32-bit processing and supports sample rates up to 384kHz PCM or 256x DSD. The USB interface operates in asynchronous mode allowing the m900 to be the clock master which makes the system immune to USB bus jitter. S/PDIF and Toslink inputs allow the m900 to enhance to any DAW interface with true reference quality D/A conversion, headphone monitoring and stereo speaker control.

Intelligent Power Supply Design

An intelligent power supply design allows for two power operation modes – LOW and HIGH. LOW power mode is from USB connector #1, which provides bus power along with data, allowing the m900 to operate from a single connection to your computer. HIGH power power mode is available by connecting the included 2A USB DC power supply to the USB connector #2, which provides additional power for harder to drive headphones.

Superb Audio Performance

Transimpedance amplifier topology coupled to a zero ohm output impedance driver provides headphone performance that is incredibly spacious and transparent with a tight, enveloping low end. Our latest generation crossfeed circuit rounds out the design by simulating an acoustic listening environment in the headphones. Familiar tracks become new again with surprise details, while audio production tasks like tracking, mixing and editing happen faster and easier.

After many years of honing our DAC and headphone amplifier designs, the m900 distills the best of what we’ve learned in a compact, rugged and simple unit. Whether in the studio, on your desk or on the road, the m900 will bring you closer to the music you love.

Features:

• USB, S/PDIF and Toslink digital inputs, supports up to 192kHz (Toslink up to 96kHz)
• Asynchronous USB interface for jitter free computer audio playback, supports up to 384kHz PCM and 256x DSD
• Dual zero ohm output impedance headphone outputs
• Unbalanced level controlled outputs via RCA for connecting to a stereo monitor system
• Compact, portable chassis perfect for travel, desktop or studio
• Mono mode, Left minus Right mode
• 6 monitoring modes: stereo, L&R swapped, left in both channels, right in both channels, left channel only, right channel only
• Channel balance adjustment
• Low power mode via USB Bus power
• High power mode via included USB 2A power supply
• 4 different DAC filter settings to tailor playback performance to personal preference
• Simple user setup menu for setup and calibration
• 7 segment LED display displays level and setup menu information
• Large rotary encoder for volume control and setup menu navigation

Brand	Grace Design
Condition	New

THD+N at Maximum Volume, 1KHZ, 22HZ-22KHZ BW:

• @1.0V out, no load: <0.002%
• @1.0V out, 32 Ohm load: <0.010%

Intermodulation Distortion SMTPE/DIN 4:1 50HZ, 7KHZ:

• @1.0V out, no load: <0.008%
• @1.0V out, 32 Ohm load: <0.009%

Frequency Response +/-3DB:

• Fs=96kHz: 0.5-45.9kHz

Dynamic Range:

• 20-22kHz bandwidth: 112 dB
• 20-22kHz bandwidth and A weighting filter: 115 dB

Output Noise:

• 20-22kHz, volume=0-90: -106dBV
• A weighting filter, volume = 0-90: -109dBV
• 20-22kHz, volume=90.5-99.5: -96dBV
• A weighting filter, volume = 90.5-99.5: -98dBV

Crosstalk:

• 100Hz: <107dB
• 1kHz: <98dB
• 20kHz: <72dB

Attenuation Range:

• 0 to -99dB, 0.5dB steps

Crosstalk Tracking Accuracy:

• +/-0.05dB

Maximum Output Level, No Load:

• Low Power Mode: +14.1dBV (5.1V)
• High Power Mode: +15.5dBV (6.0V)

Impedances:

• Headphone Output: 0.08 Ohms
• Line Output: 47.5 Ohms

Input Lock Range:

• S/PDIF
• Sample Rate (44.1kHz): Lock Range (43870-45420Hz)
• Sample Rate (48kHz): Lock Range (46590-49220Hz)
• Sample Rate (88.2kHz): Lock Range (87760-90830Hz)
• Sample Rate (96kHz): Lock Range (93520-98430Hz)
• Sample Rate (176.4kHz): Lock Range (175700-181640Hz)
• Sample Rate (192kHz): Lock Range (187050-196380Hz)
• TOSLINK
• Sample Rate (44.1kHz): Lock Range (43900-45410Hz)
• 60Hz
• Sample Rate (48kHz): Lock Range (46590-49190Hz)
• 60Hz
• Sample Rate (88.2kHz): Lock Range (87840-90830Hz)
• 60Hz
• Sample Rate (96kHz): Lock Range (93520-97530Hz)
• USB supported sample rates
• 44.1, 48, 88.2, 96, 176.4, 192, 352.8, 384kHz

Power Consumption:

• Max, High Power mode: 8.0W
• Max, Low Power mode: 2.5W

Dimensions:

• 4" x 5.25" x 1.8"

Headphone Output Power / Low Power Mode:

• S/PDILoad Resistance Ohms (4): 1 Channel Driven (80)
• S/PDILoad Resistance Ohms (8): 1 Channel Driven (140)
• S/PDILoad Resistance Ohms (16): 1 Channel Driven (310)
• S/PDILoad Resistance Ohms (20): 1 Channel Driven (350)
• S/PDILoad Resistance Ohms (32): 1 Channel Driven (600)
• S/PDILoad Resistance Ohms (50): 1 Channel Driven (560)
• S/PDILoad Resistance Ohms (300): 1 Channel Driven (83)
• S/PDILoad Resistance Ohms (600): 1 Channel Driven (40)
• S/PDILoad Resistance Ohms (4): 2 Channels Driven (22)
• S/PDILoad Resistance Ohms (8): 2 Channels Driven (45)
• S/PDILoad Resistance Ohms (16): 2 Channels Driven (90)
• S/PDILoad Resistance Ohms (20): 2 Channels Driven (100)
• S/PDILoad Resistance Ohms (32): 2 Channels Driven (175)
• S/PDILoad Resistance Ohms (50): 2 Channels Driven (280)
• S/PDILoad Resistance Ohms (300): 2 Channels Driven (83)
• S/PDILoad Resistance Ohms (600): 2 Channels Driven (40)

Headphone Output Power / High Power Mode:

• S/PDILoad Resistance Ohms (4): 1 Channel Driven (925)
• S/PDILoad Resistance Ohms (8): 1 Channel Driven (1800)
• S/PDILoad Resistance Ohms (16): 1 Channel Driven (1900)
• S/PDILoad Resistance Ohms (20): 1 Channel Driven (1575)
• S/PDILoad Resistance Ohms (32): 1 Channel Driven (1020)
• S/PDILoad Resistance Ohms (50): 1 Channel Driven (680)
• S/PDILoad Resistance Ohms (300): 1 Channel Driven (115)
• S/PDILoad Resistance Ohms (600): 1 Channel Driven (57)
• S/PDILoad Resistance Ohms (4): 2 Channels Driven (240)
• S/PDILoad Resistance Ohms (8): 2 Channels Driven (490)
• S/PDILoad Resistance Ohms (16): 2 Channels Driven (940)
• S/PDILoad Resistance Ohms (20): 2 Channels Driven (1030)
• S/PDILoad Resistance Ohms (32): 2 Channels Driven (950)
• S/PDILoad Resistance Ohms (50): 2 Channels Driven (650)
• S/PDILoad Resistance Ohms (300): 2 Channels Driven (115)
• S/PDILoad Resistance Ohms (600): 2 Channels Driven (57)