pcm.ossmix {
    type dmix
    ipc_key 1024          # must be unique!
    ipc_perm 0660         # sound for everybody (at least in your group)
    slave {
        pcm {
                type hw
                card 0
                device 0
        }

        period_time 0
        period_size 1024  # must be power of 2
        buffer_size 8192  # dito. It
        rate 48000        # with rate 8000 you *will* hear,
                          # if ossmix is used :)
    }
    bindings {
        0 0
        1 1
    }
}

pcm.dsp0 {
    type plug
    slave.pcm "ossmix"     # use our new PCM here
}

ctl.mixer0 {
    type hw
    card 0
}

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