Dynamic change of Audio Destination

For phone and tablet, we often need to switch from headset to speakers or HDMI and the number of output channels may be dynamic.

How should web audio handle such cases?  There are two issues here:

1. whether audio destination node should provide hooks to indicate that the user may have switched from headset to speakers or HDMI and channel number changed?
And whether the behavior of effects such as spatialization should really be output-dependent?

2. whether maxNumberOfChannels should be able to change dynamically?

Best Regards

James