A delay is inherent on any analog line in on a Sonos device, but the line out, to any other device should be in sync with all other Sonos devices. 

It is not clear how you have this setup, and connected, and how you’re noticing the delay. There are extremely rare cases where a CONNECT needs to be rebooted, toget the chipset back in sync with all other Sonos devices, but that won’t address the issue of the delay on the line in. 

Hi @mattfort 

Welcome to the Sonos Community!

Sorry to hear of this sync issue you are having with your Connect. If @Airgetlam has not already solved this for you, does your amplifier have a “Direct” - or similar - button for the input you’ve plugged the Connect into?

The reason I ask is that I had a stereo Yamaha amplifier that had a CD Direct button that would cut out additional Bass/Treble/Balance circuitry and result in a cleaner sound. Some digital amplifiers that do this processing digitally can induce a delay, and these devices often have such a button to bypass the circuits in order to eliminate the delay.

I hope this helps.

I’m also bothered by the buffering delay from the analog line-in of the Connect product. 

I have a digital music player and I normally plug the digital output from that into my stereo amplifier to listen to the passive stereo speakers directly wired to the amp.  If I plug the analog output of the stereo amplifier into the line-in of the Connect, then all my wireless Sonos speakers will exhibit severe latency compared to the sound coming out of the speakers directly wired to the amplifier.

The workaround is to instead feed the analog outputs of my digital music player into the analog line-in of the Connect, and then take the analog output of the Connect and plug that into my stereo amplifier. 

I’m not entirely happy with this configuration:  it means that my Sonos speakers can only stream audio from my digital music player.  Other audio sources connected to my amp, such as a turntable or CD player, cannot reach my wireless Sonos speakers with this configuration.

The other annoyance with this configuration is that there is no purely digital signal path from my local music collection to the Sonos wireless network.  The player accessing my local online music has to convert the digital to analog to get into the Sonos Connect, which then immediately converts it back to digital. 

I’m puzzled that Sonos didn’t think to include digital inputs for the Connect product.

Do you have a tape loop (tape in/out) on your amplifier? I would connect the line-in on the Connect to Tape In, and line out to tape out. (I hope that’s the right way round, it’s been a while!) Doing that allows the connect to work like a tape deck where the source you select on your amplifier will be fed into the tape in, and effectively the Connect. If you listen to the tape out on the amplifier, instead of say the CD or turntable, then the sound is what has been digitised by the connect from Line In, and should be much closer in sync. 

The Connect has to take the analog sound from Line In, convert it to digital and then send that signal to the other Sonos speakers. This is not instantaneous, hence the delay. The issue is you have plugged your Line In on the Connect to an analogue output, which is (for the amplifier) bypassing that required processing to make the sound available to other Sonos speakers. 

Do you have a tape loop (tape in/out) on your amplifier?

That’s a brilliant suggestion and would definitely solve the issue.  Unfortunately, I don’t have a tape in / out / monitor on my amplifier and as far as I know amplifiers have not provided anything like them in the decades since the heyday of home tape recording. 

The old stereo receivers with true tape monitoring were great -- you could record a vinyl LP to a 3-head tape deck and compare the original LP source to the sound from the recording as it was being taped.

If I still had my old 1980s Teac stereo receiver I would feed its tape out to the line-in of the Connect and feed the line-out of the Connect to the tape in of the receiver. Any source I select on the amplifier would then be fed to the Connect, and I would be able to use the tape monitor switch to listen to the Connect’s output in sync with the Sonos speakers.