[David Liao]

Thank you for your message.

If the drummer would like to mix his mics (bass, snare, and overhead) and backing tracks together in Reaper and then send combined mix from Reaper to FarPlay, he should use ReaRoute.

1. Have the drummer install ReaRoute. He might have already done this when he installed Reaper. If not, have him re-run the Reaper installer and make sure to checkmark the option for installing the ReaRoute ASIO driver.
   
   Screenshot is from https://forum.cockos.com/showthread.php?t=224898. For more info, see https://forum.cockos.com/showthread.php?t=205415.
2. Have FarPlay use ReaRoute for input and output: In FarPlay’s Devices > Microphone: and Headphones: pull-down menus, have the drummer choose ReaRoute ASIO.
3. The drummer needs to configure Reaper to send audio out through ReaRoute and to receive audio from ReaRoute. I will work on screenshots for this later today.

Thank you,
David Liao