Question:
How can I get the same signal fed out of both the Main and Aux outs?

Answer:
Need to run a duplicate signal to two different destinations? like perhaps the house sound system and your amp on stage ?

The PC3 offers a quick and easy feature that does just that:

1) Go to MASTER mode and press [OUTPUT]:

2) Set the “Aux Out Pair Mode” to “Mirror Primary Outputs”

Done. Now any audio being routed to the Main outs (Pri.) is also simultaneously being sent to the Aux outs (Sec.).