pcm.dshare {
    type dmix
    ipc_key 2048
    slave {
        pcm "hw:0,0"
        rate 44100
        period_time 0
        period_size 1024
        buffer_size 8192
        channels 4
    }
    bindings {
        0 0
        1 1
        2 2
        3 3
    }
}

pcm.frontx {
   type plug
   slave {
       pcm {
           type plug
           slave {
               pcm "dshare"
               channels 4
           }
           ttable.0.0 1
           ttable.1.1 1
       }
       channels 6
   }
   route_policy default # mono -> stereo 
}

pcm.rearx {
   type plug
   slave {
       pcm {
           type plug
           slave {
               pcm "dshare"
               channels 4
           }
           ttable.0.2 1
           ttable.1.3 1
       }
       channels 6
   }