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Input Connections
The input / output / interface connections highlighted earlier in this manual are detailed below. Please contact us if you have any
questions regarding cable terminations or pinout specifications.
BALANCED ANALOG INPUTS - The balanced stereo analog input is provided via female XLRs. Connection is made using standard
balanced XLR cables. This input is wired to the pin 1 shield, pin 2 positive pin 3 negative XLR standard.
UNBALANCED ANALOG INPUT - This stereo input is provided for interfacing with consumer level (-10dBv) unbalanced analog
sources. Connections are made using standard RCA cables.
AES3 DIGITAL INPUT - The stereo AES3 input is provided via one female XLR connector. This conforms to the AES3 standard. Use
of high quality 110 Ohm balanced cable is highly recommended.
S/PDIF COAXIAL INPUT - Standard coaxial stereo digital input. The input impedance is 75 Ohms. Use a quality 75 Ohm cable for
connections to this input.
TOSLINK INPUT - Standard stereo optical input connector for use with consumer devices. Use a standard TOSLINK optical cable for
connections to this input.
USB INPUT - The stereo USB input for connection to a host computer. Use a standard USB type A -to- type B mini cable (included
with your m903). The type A connector is to be plugged in to the HOST PC and the type B mini connector is to be used with the
m903 input.
Output Connections
STEREO HEADPHONE OUTPUTS - Headphone outputs are provided via two ¼” TRS (Tip, Ring, Sleeve) jacks. These outputs are
wired in parallel. Connection to headphones should be made using standard ¼” TRS stereo connectors.
UNBALANCED LINE OUTPUTS - A stereo pair of unbalanced line level outputs are provided via two RCA jacks. These outputs
should be connected to powered speakers or power amplifiers using standard unbalanced RCA cables.
BALANCED LINE OUTPUTS - A stereo pair of balanced line level outputs are provided via two ¼” TRS jacks. These outputs should be
connected to powered speakers or power amplifiers using standard balanced cables. Connection to an unbalanced input is also
possible. See figure 1 and 2 below for proper termination.
pin 1
pin 2
pin 3
TIP
RING
SLEEVE
Balanced Input XLR
Balanced Output 1/4” TRS
figure 1 balanced 1/4” TRS to XLR
SHIELD
HOT
GND
RING IS OPEN
TIP
RING
SLEEVE
Unbalanced Input RCA
Balanced Output 1/4” TRS
figure 2 balanced 1/4” TRS to unbalanced RCA
Selecting an Input Source
The m903 allows for selection from a variety of analog and digital input sources. The rotary input selector switch is used to choose
the input source for both the headphone amplifier and line outputs.
ANALOG INPUTS - The m903 provides both balanced and unbalanced stereo inputs. To select either of these analog inputs, rotate
the input selector to the desired input. When an analog input is selected, the m903’s internal DAC is turned off.
DIGITAL INPUTS - The m903 provides the following digital input sources: AES3, S/PDIF, TOSLINK and USB. The AES3, S/PDIF and
TOSLINK inputs support audio data with sample rates from 32kHz to 192kHz and 24 bits. The USB input supports audio data with
sample rates from 44.1kHz to 192kHz with 24bit resolution.
