Remapping channels to/from other devices (examples): (remember pacmd)
# from XR18 to OSB (inputs)
load-module module-remap-source channels=2 source_name=IUSB1S source_properties=device.description=IUSB1S remix=no master=alsa_input.usb-BEHRINGER_X18_XR18_5BEFB5B8-00.multichannel-input master_channel_map=front-left,front-right channel_map=front-left,front-right
load-module module-remap-source channels=2 source_name=IUSB3S source_properties=device.description=IUSB3S remix=no master=alsa_input.usb-BEHRINGER_X18_XR18_5BEFB5B8-00.multichannel-input master_channel_map=rear-left,rear-right channel_map=front-left,front-right
# from CH9 to XR18 (outputs)
load-module module-remap-sink channels=1 sink_name=OUSB9 sink_properties=device.description=OUSB9 remix=no master=alsa_output.usb-BEHRINGER_X18_XR18_5BEFB5B8-00.multichannel-output master_channel_map=aux0 channel_map=mono
# from CH10 to XR18 (outputs)
load-module module-remap-sink channels=1 sink_name=OUSB10 sink_properties=device.description=OUSB10 remix=no master=alsa_output.usb-BEHRINGER_X18_XR18_5BEFB5B8-00.multichannel-output master_channel_map=aux1 channel_map=mono
# from CH13S to XR18 (outputs)
load-module module-remap-sink channels=2 sink_name=OUSB13S sink_properties=device.description=OUSB13S remix=no master=alsa_output.usb-BEHRINGER_X18_XR18_5BEFB5B8-00.multichannel-output master_channel_map=aux6,aux7 channel_map=front-left,front-right
# from CH15S to XR18 (outputs)
load-module module-remap-sink channels=2 sink_name=OUSB15S sink_properties=device.description=OUSB15S remix=no master=alsa_output.usb-BEHRINGER_X18_XR18_5BEFB5B8-00.multichannel-output master_channel_map=aux4,aux5 channel_map=front-left,front-right
# XR18 input : alsa_input.usb-BEHRINGER_X18_XR18_5BEFB5B8-00.multichannel-input
# XR18 output: alsa_output.usb-BEHRINGER_X18_XR18_5BEFB5B8-00.multichannel-output