pcm.dmixer {
type dmix
   ipc_key 1024
   ipc_key_add_uid false
   ipc_perm 0660
   slave {
      pcm "hw:1,3" 
      rate 48000
      channels 2
      period_time 0
      period_size 1024
      buffer_time 0
      buffer_size 4096
   }
}

pcm.!default {
   type plug
   slave.pcm "dmixer"
}