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m903 Key Features
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Stereo analog inputs - balanced (+4dBu) XLR and unbalanced (-10dBv) RCA.
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Ultra low distortion 24-bit /192khz DAC accepts stereo digital input sources in AES3, S/PDIF, TOSLINK (optical) and USB for-
mats with auto sample rate detection and digital de-emphasis filter.
•
s
-lock
tm
dual stage PLL (phase lock loop) circuitry for the ultimate in low jitter clocking and sonic integrity.
•
Two sets of line level outputs provided via RCA and ¼ TRS jacks for connection to stereo monitors.
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Front panel rotary encoder provides precision level control of both headphone and the line output levels. Level adjustments
are made in 0.5dB steps within a 95dB range.
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0.05dB channel level matching to ensure true stereo balance at any monitoring level.
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Large, white 7-segment display is used to show headphone and stereo main output levels.
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X-feed (crossfeed) simulates the acoustics of a loudspeaker listening environment which can significantly improve imaging
while reducing listening fatigue when using headphones. This feature employs carefully designed signal cross-feed, filtering
and delay circuits to simulate hrtf (head related transfer functions).
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High current transimpedance output amplifier design drives 8 ohm loads. The m903 was specifically designed with low im-
pedance headphones in mind.
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Only the highest quality 0.5% metal film resistors are used throughout and there are no electrolytic capacitors in the signal
path. Sealed gold contact relays are used for all signal switching.
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Infrared remote control for level control, left/right balance, mute and more when using the optional remote control unit.
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5 Year transferable warranty on parts and labor.
m903 Frontpanel Controls / Features
1
ILLUMINATED POWER SWITCH - illuminates green when unit is powered on.
2
ROTARY INPUT SELECTOR SWITCH - selects between all available inputs.
3
s
-lock
tm
INDICATOR LED - illuminates when
s
-lock
tm
is active.
4
SAMPLE RATE INDICATOR LEDS - auto sample rate detection from selected digital input source.
5
CROSSFEED INDICATOR LED - crossfeed circuitry is user activated in setup menu or via the optional remote.
6
OUTPUT LEVEL/EDIT ROTARY ENCODER - This stepped rotary encoder controls the selected output level in .5dB increments.
This encoder is also used to adjust other settings found in the setup menu.
7
OUTPUT SELECTION LEDS – These LEDS indicate which output is currently selected by the user and under interface control.
8
OUTPUT LEVEL / SETUP MENU DISPLAY - This blue, 2 digit display shows the current relative output level values based on the
position of the main level rotary encoder. The range of this display is 0 to 99. Note the decimal represents a 0.5dB increment.
This display is also used to give the user information in the setup menu.
9
HEADPHONE OUTPUTS – Two stereo headphone output jacks wired in parallel.
FS
44
48
88
96
176
192
INPUT
Xfeed
OUTPUTS
s-Lock
AES
BAL
UNBAL
S/PDIF
TOS
USB
GRACE DESIGN, USA
VOLUME
push
reference headphone
amplifier / DAC
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