Meridian 566 User Manual page 21

Note that you should not configure any of the analogue sources
connected directly to the Control Unit in your system. Otherwise
selecting one of these will change the digital input on the Digital
to Analogue Converter which could interrupt a source you are
tape recording.
To reset the Digital to Analogue
Converter
You can reset the Digital to Analogue Converter to its initial
configuration using the following procedure:
Turn off the Digital to Analogue Converter, using the power
switch on the back panel.
Turn on the power again while holding down the Phase key
on the front panel.
All the indicators on the front panel will be illuminated for one
second.
The inputs will be programmed so that they are only selected by
the appropriate front panel key.
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