[LAU] Output to 2 sound cards simultaneously

[Mark Constable]

I've read this a couple of times over the years but it still
does not make much sense (to me)...

 http://alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html

As a baseline, say I started with this, where could I go
from here to get an app (ie; Amarok) to play back out two
soundcards at once ?

# cat .asoundrc
pcm.NVidia { type hw; card NVidia; }
ctl.NVidia { type hw; card NVidia; }

pcm.USX2Y  { type hw; card USX2Y; }
ctl.USX2Y  { type hw; card USX2Y; }

pcm.shared {
  type dshare
  ipc_key 321456  # any unique value
  ipc_key_add_uid true
  slave NVidia
  slave USX2Y
  bindings {
    0 0
    1 1
  }
}

--markc