Rega Saturn-R - Manual (Page 17)

REAR LED INDICATOR FUNCTIONS
Three LED’s are located on the back panel.
Power - The USB takes its power from the connected computer.
This will stay on whilst connected even if the Saturn-R is off.
Comm - The USB input is active and communicating with the connected computer.
Dta - This indicates data is flowing through the USB input. For example, it will light when
a track is played using a media player or when an Internet radio station is active.
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