HTML Audio play sounds on different channels

I like to play 2 HTML Audio sounds on 2 different AudioDestination Channels. I've connected a USB Sounddevice with 2 Outputs. The AudioDestination.channelCount is 4.

I know this blog post: http://ift.tt/WMHaOp and I think this is pointing me to the correct way, but the example is only playing one sound with different channels. So my idea is to create a ChannelMerger to merge the 2 sounds and connect the ChannelMerger to my AudioDestination. Am I right or is this completely wrong?