pcm.usb1 {
type dmix
ipc_key 1234 
ipc_key_add_uid false
ipc_perm 0660
slave {
pcm "hw:0,0"
rate 48000
channels 2
period_time 0
period_size 1024
buffer_time 0
buffer_size 8192
}
}

pcm.usb2 {
type dmix
ipc_key 4321 
ipc_key_add_uid false
ipc_perm 0660
slave {
pcm "hw:1,0"
rate 48000
channels 2
period_time 0
period_size 1024
buffer_time 0
buffer_size 8192
}
}