Thanks for your reply.
When the receiver is generating the audio signal there is a delay between the receiver speakers and Sonos speakers due to wifi transmission, processing, etc.
One work around would be for receiver companies to create a 'Receiver Delay' similar to the television lipsync adjustments (naturally you couldn't have both enabled at the same time). That way the receiver can integrate into any wireless speaker system no matter what roadblocks are put in it's way. A few years back I emailed back and forth with Yamaha customer service (only because that's the make of my main receiver) and I'm not sure they understood what I was talking about.
Conversely one might allow Sonos to generate the signal (I'm thinking primarily of Pandora, radio on the internet, server) and feed it into the receiver. In this case, as you mention--due to surround processing, the receiver is out of sync and behind the wireless speakers.
Earlier incarnations of Sonos software included a variable delay feature to enable syncing all the speakers (Sonos and receiver) in this scenario.
Then Sonos removed the delay adjustment through software updates in an attempt to force users to embrace a 'Sonos Only' system. Sonos executives are on record declaring 'The A/V Receiver is Dead' (
http://www.cnet.com/news/sonos-the-av-receiver-is-dead/). That's ridiculous for a host of reasons.
The current Sonos 'solution' is to run your receiver in Pure Direct. What's the point of having surround speakers then? Depending on the receiver in Pure Direct you experience a delay (in my case around 70ms).
This latency business has legs in the Sonos website forum but to date Sonos has just ignored the posts or thrown the Pure Direct solution at users.
I understand that in an ideal world wired is the way to go. I have wired speakers on my deck and in my kitchen. If I ran wires everywhere I needed, wireless speakers wouldn't be attractive at all. Frankly MusicCast wouldn;t have much of a market. But I don't want to tear the walls of my house apart just to put more speakers in other rooms.
To me the occasional glitch due to wifi/transmission is tolerable as long as a massive design flaw isn't BAKED into the system to begin with.
I experimented with Sonos and ended up with only one speaker in the basement in order to manage the delay. I would gladly invest with MusicCast (5-6 speakers) if their solution can keep everything in reasonable sync.