My audio interface (MOTU M6) has 4 line-outs, meaning I can have 2 independent L/R stereo outputs. That means I can play my VST and route the output audio to outputs 1 and 2 and I can send the backing tracks to outputs 3 and 4. That would be ok if there wasn’t a CLICK sound that I want to send, independently, to my band’s members It seems I would need another line-out for the click, but MOTU has only 4 outputs.
You can’t solve it with that interface.
You want 3 different sets of outputs, but you only have 2.
GP can route all sorts of different ways internally, but in the end the interface determines how many physical outputs you have.
If you choose to run the backing tracks and the click track in mono, you can achieve what you want by sending one signal to each side of the stereo pair—but I’m assuming you want stereo output for the backing tracks.
Why not to mix the backtracks and the keys in GP internally?
So you would only need 3 outputs (2 keys, 1 click).
I’m using this solution with my presonus interface, which also has 4 outputs and it’s working fine for me.
I’m assuming you want the backing tracks to output to different devices/speakers than your VST instrument. If not, then you can do as @Stoffel suggested and mix them into your main output.
Because I want our sound engineer to deal with the backing track independently. He may want to raise the BT volume, for example, and that would raise my instrument volume too. He may also try different equalization parameters both for my instrument and BT.
Then you should work on your backing tracks and your keyboard sounds, so they sound good with identical EQ.
Except percussion.
For percussion I would use separate outputs because precussion has to be in context with the drums.
I know the thread is a bit old, but I just came across it today. It occurred to me that some interfaces offer an independent output for headphones which may be suitable for either the click or the backing tracks if you’re not already using it e.g. for personal monitoring. Remember that headphone outputs aren’t balanced may need to go via a DI.