Why a cable? If one pod is the master and the other one a slave nearby, it should be easy to send the audio data to the slave from the master via bluetooth or similar low power, short range radio protocol.

AFAIK it is only hard to sync two boxes with sound via a 'bulky and buffery' protocol like WiFi. Also, we humans can tolerate visual artefacts easily, but async, skipping sounds are a special kind torture.