As a reasonably techie guy I’ve been helping my neighbour set up his domestic sound system. He has a Sonos driven output in 5 separate rooms. There is a mixture of Sonos 5 speakers, Ports feeding AV amplifiers and an Amp running a pair of speakers. All the rooms are very separate acoustically apart from the lounge, which has a large opening into the kitchen/dinner area. The lounge has a Port feeding a good Sony AV surround sound amplifier and the kitchen has an Amp driving a pair of passive speakers. And so he is suffering from the dreaded ‘stadium echo’ effect when playing music in both the kitchen and lounge. The mechanism is easy to understand; the Sonos kit is all synchronised together but the Sony AV system adds its own delays after the output from the Sonos Port. Because the Sony amp, along with many other AV systems, is designed such that the video output is always lip synced with the TV picture, changing from surround to direct modes does not affect the audio delay. So it is impossible to reduce the Sony Amp audio processing delay to zero to ‘solve’ the problem.
I’ve spent quite some time looking back through the Sonos Community blogs. The earliest reference I’ve found so far to the AV Amp delay problem was 17 years ago
There are many, many other threads along the same topic. The root cause of the problem is well understood and explained but there is always an excuse why a fix can’t be offered. Yes, it would be difficult to implement variable delays that would allow any combination of Sonos and AV amps to work together. But, from the blogs, for most installations you only need to delay a single Sonos output device relative to the one feeding the AV receiver. Following the 80:20 rule that would fix the problem for most people.
Technically it is possible. There might be RAM constraints to how much delay can be introduced. But RAM is cheap. So I do not understand why Sonos is still not offering even a partial fix :-(