Instruction Manual
850P Reference Dual-Mono Preamplifier 
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10 
If you want to turn the display off, press and hold 
the “Display” button for 2 seconds. When the 
display is turned off, it will still come back on for a 
short period of time whenever you press any of the 
buttons located on the front panel or the remote 
control, using the brightness level that was 
previously set; the display will automatically turn off 
again once you are done. To turn the display back 
on, simply press and hold the “Display” button for 2 
seconds. 
The “Input X” and “Input W” buttons allow you to 
choose which input source you wish to listen to. The 
MOON 850P dual-mono preamplifier has a total of 
seven (7) inputs; The first three (3) inputs are fully-
balanced and use XLR connectors labeled B1, B2 
and B3. The next four (4) inputs are single-ended 
and use RCA connectors labeled S1, S2, S3 and S4. 
Assuming that you’re currently listening to a source 
component connected to input B1, the “X” allows to 
sequentially scroll forward through the available 
inputs from B2 to S4. The “W” button allows you to 
sequentially scroll backwards from S4 to B2.  
Holding down either the “X” or “W” input buttons 
will allow only a single change of the selected input.  
You must press the button again to select the next 
or previous input. 
The rotary “volume” control determines the gain 
setting, which ranges from ‘0.0dB’ (no output) to 
’80.0dB’ (full output). This control does not function 
like a typical volume: When you rotate the dial, 
either clockwise to raise the volume or counter-
clockwise to lower the volume, you are actually 
engaging a precision optical encoder which selects, 
via a relay network, very high quality thin film 
resistors that the audio signal passes through. The 
result is a proprietary gain circuit, called M-Ray, 
that doesn’t degrade the audio signal regardless of 
the setting, unlike 
all potentiometer based circuits.  
Since this circuitry operates in a fully balanced 
differential mode, no noise is introduced to the 
audio signal. Futhermore, since there are no actual 
moving parts, this technology has a minimum life 
expectancy of one million rotations. 
The  MOON 850P preamplifier provides a range of 
five-hundred and thirty (530) unique volume 
settings. This is achieved as follows: Within the 
0.0dB to 30.0dB range, you can increase and 
decrease the volume in 1.0dB steps. From the 
30.0dB to 80.0dB range, you can increase and 
decrease the volume by either 0.1dB or 1.0dB steps; 
By rotating the volume control slowly, the level will 
change by 0.1dB increments. A quicker rotation will 
change the volume in 1.0dB increments. 
Note: To change the balance between the left and 
right channels, please refer to the section “Remote 
Control Operation”. 
The “Setup” and “OK” buttons are used for 
programming the numerous software functions 
available on this preamplifier. The next section, 
entitled “Software Setup”, explains their usage in 
detail. 










