The following steps will allow you to connect an outboard effects processor through the subgroups when all Aux sends are being used:
1. All channels you wish to send to this processor must be routed to 1-2 with the button next to the fader. MAIN should also be engaged.
2. Bring the SUB 1 fader to the "zero" position.
3. Verify that the LEFT and RIGHT buttons next to the SUB 1 fader are NOT engaged.
4. Connect a cable from SUBGROUP OUT 1 to the input of the effects processor.
5. Connect the left and right outputs of the processor to the LEFT and RIGHT LINE INPUTS of a stereo channel (27/28 for this example)
6. Bring the stereo channel fader to the "zero" position.
7. Engage the MAIN button on channel 27/28.
8. Verify the 1-2 button on channel 27/28 is NOT engaged, otherwise a feedback loop will occur.
The overall input volume to the processor will be controlled via the SUB 1 fader. The overall output of effects to the Main Mix will be controlled with the channel 27/28 fader.