I have two devices playback_bt (Connects to BT chip) and aduplex_rtp (which delivers audio to a device/speaker over rtp). I can use aplay to play sound to them individually. I want to be able to write sound to the Loudspeaker device and it come out of both devices simultaneously. Below is my asound.conf. This must me done with just ALSA and preferably without using the multi plugin.