Grace Design m900 Portable Headphone Amp / DAC / Preamp

A portable, desktop-friendly combination headphone amplifier / DAC / preamp, the Grace Design m900 is made to offer 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 Grace's large monitor controllers, but in a unit that's rugged, portable, and surprisingly affordable. It uses the latest generation AKM 4490 chip, which features 32-bit processing and support for sample rates up to 384 kHz PC or 256x DSD. It has a USB interface that operates in asynchronous mode, which enables it to be the clock master, making the system immune to USB bus jitter. S/PDIF and Toslink inputs let the m900 connect to any DAW interface with true reference-quality D/A conversion, headphone monitoring, and stereo speaker control. It also features an intelligent power supply design that offers 2 power operation modes - LOW and HIGH. LOW power mode is from USB connector #1, which provides bus power along with data, so it can operate from a single connection to your computer. The HIGH power power mode is available by connecting the included 2A USB DC power supply to the USB connector #2, which brings additional power to drive headphones. Its transimpedance amplifier topology coupled to a zero-ohm output impedance driver delivers headphone performance that's incredibly spacious and transparent along with a tight, enveloping low end. Grace's latest generation crossfeed circuit rounds out the design by simulating an acoustic listening environment in the headphones, offering surprise details that make familiar tracks new again, while audio production tasks like tracking, mixing and editing can be done faster and easier.

Grace Design m900 Features:

• USB, S/PDIF, and Toslink digital inputs, supports up to 192 kHz (Toslink up to 96 kHz)
• Asynchronous USB interface for jitter-free computer audio playback, supports up to 384 kHz 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
• 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
• Made in Lyons, CO USA
• Five year transferable Warranty

Grace Design m900 Specifications:

• THD+N 1kHz, 22 Hz-22 kHz BW:
  • @1.0V out, no load: < 0.002%
  • @1.0V out, 32 Ohm load: < 0.010%
• Intermodulation Distortion SMTPE/DIN 4:1 50 Hz, 7 kHz:
  • @1.0V out, no load: < 0.008%
  • @1.0V out, 32 Ohm load: < 0.009%
• Frequency Response +/-3dB: Fs = 96 kHz: 0.5 - 45.9 kHz
• Dynamic Range:
  • 20-22kHz bandwidth: 112 dB
  • 20-22kHz bandwidth and A weighting filter: 115 dB
• Output Noise:
  • 20 - 22 kHz, volume = 0 - 90: -106 dBV
  • A weighting filter, volume = 0 - 90: -109 dBV
  • 20 - 22 kHz, volume = 90.5 - 99.5: -96 dBV
  • A weighting filter, volume = 90.5 - 99.5: -98 dBV
• Crosstalk:
  • 100 Hz: < 107dB
  • 1 kHz: < 98dB
  • 20 kHz: < 72dB
• Attenuation Range: 0 to -99 dB, 0.5 dB steps
• Channel Tracking Accuracy: +/-0.05 dB
• 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 — Sample Rate Lock Range
  • S/PDIF:
    • S/PDIF:
  • 44.1 kHz 43870-45420 Hz
    • 44.1 kHz 43870-45420 Hz
  • 48 kHz 46590-49220 Hz
    • 48 kHz 46590-49220 Hz
  • 88.2 kHz 87760-90830 Hz
    • 88.2 kHz 87760-90830 Hz
  • 96 kHz 93520-98430 Hz
    • 96 kHz 93520-98430 Hz
  • 176.4 kHz 175700-181640 Hz
    • 176.4 kHz 175700-181640 Hz
  • 192 kHz 187050-196380 Hz Toslink:
    • 192 kHz 187050-196380 Hz
    • Toslink:
  • 44.1kHz 43900-45410 Hz
    • 44.1kHz 43900-45410 Hz
  • 48 kHz 46590-49190 Hz
    • 48 kHz 46590-49190 Hz
  • 88.2 kHz 87840-90830 Hz
    • 88.2 kHz 87840-90830 Hz
  • 96 kHz 93520-97530 Hz
    • 96 kHz 93520-97530 Hz
  • USB supported sample rates, kHz: 44.1, 48, 88.2, 96, 176.4, 192, 352.8, 384
  • 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 - Output Power mW:
  • Load Resistance, Ohms 1 Channel Driven 2 Channels Driven
  • 4 80 22
  • 8 140 45
  • 16 310 90
  • 20 350 100
  • 32 600 175
  • 50 560 280
  • 300 83 83
  • 600 40 40
  • Headphone Output Power / High Power Mode - Output Power mW:
  • Load Resistance, Ohms 1 Channel Driven 2 Channels Driven
  • 4 925 240
  • 8 1800 490
  • 16 1900 940
  • 20 1575 1030
  • 32 1020 950
  • 50 680 650
  • 300 115 115
  • 600 57 57