With a Yamaha receiver simply set the audio option to 'audio sync' instead of 'lip sync' when linking zones. You can cast HDMI / optical etc from zone to zone with MusicCast. To make it easier (so the end user doesn't have to press the link button in the amp) simply press Main Sync - it leaves the main zone running natively AND plays the second zone in sync. Super simple.
This industry is not getting cheaper and cheaper, we're simply convincing ourselves that we have to push the cheapest option to customers. #makesonosgreatagain