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1. Power Jack
Attach the power cord here.
2. USB Port 
Provides communication with a computer for use with MX-Edit
TM
 Editor/Librarian 
software and MX400 plug-in window using a standard USB cable. When the MX400 is 
connected to a computer via USB, the blue USB LED next to the main display will light.  
3.  Footswitch Input
The optional Lexicon® LEX-DFS 2-button footswitch can be plugged into this TRS 
jack for remote control of the MX400 (see page 34 for more information). 
4. MIDI In, MIDI Thru
Provides MIDI operation capabilities. Two 5-pin MIDI DIN connectors are available for 
MIDI IN and MIDI THRU. (See page 50 for MIDI Implementation charts.)
5. S/PDIF Digital In/Out 
Digital input accepts 44.1kHz / 48kHz signals. When the S/PDIF digital input is select-
ed and active, the S/PDIF LED on the front panel lights. 
Important: It is recommended that you do not connect any digital device to the 
MX400’s S/PDIF inputs that transmits at sample rates other than 44.1 kHz or 48 kHz 
(such as 96kHz). Doing so can cause unpredictable performance. Make sure the device 
you are connecting to the MX400’s S/PDIF In is set as the Clock Master (if that option 
is available) and transmitting at a sample rate of 44.1kHz or 48kHz only. As with any 
other connection, if you need to unplug the S/PDIF cable, it is recommended that you 
switch to the analog inputs (see Input Source in the System menus) or bypass both 
processors before disconnecting the cable. 
The Rear Panel
6
The ReAR PANeL