I have a “monitor” (input monitoring) button on my Echo 2 USB device. Would that be it?
Specs says:
-Each input may be monitored, or passed through to the outputs. The slider control sets
the monitor level from muted at the bottom to full (0dB) at the top.
There are two different monitoring modes to choose from. To switch from one to the
other press the MON button for two seconds. The MON indicator LED will either be on
steady or slowly flash to show which monitor mode is currently being used.
Steady LED – “Live” mode. Each input is monitored equally through both
outputs (center panned).
Flashing LED – “Studio” mode. IN 1 is monitored through OUTL (panned hard
left) and IN 2 is monitored through OUTR (panned hard right).