If TV audio is received by a Sonos Amp over its HDMI-ARC port, the buffering of the Audio to its wired speakers is minimal and virtually non-perceptible, as the audio needs to be in lip-sync with the video on screen. This ‘immediate’ audio-output also applies to its ‘bonded’ (not grouped) rear left/right surrounds and Sub, which in the Sonos App, would all form part of the same Sonos room.
In complete contrast to this, Sonos devices/rooms can be ‘grouped’ together … that technically could mean up-to 31 other Sonos rooms could be grouped to an Amp in a worse-case scenario, across either or both a wireless, or wired, network and so to achieve this demand, a higher level of audio-buffering is required for Sonos grouped room playback - The minimum audio buffer size is 75ms as you rightly mention for this scenario, but it can be increased in the App up-to a 2 second buffer delay.
This larger buffer is of course needed in some instances to cater for some poorly configured Home networks (interference from other devices etc.) or for the case where a user chooses to group a large number of Sonos rooms.
Line-in audio too, can often be quite demanding so that type of input into Sonos has a 75ms minimum buffer delay by default aswell, to allow the audio to play in perfect sync across any/all grouped rooms.
So getting speakers to all play in sync, particularly when a setup is involving non-Sonos Amps and Receivers within grouped-room playback is likely going to present some challenges, particularly if trying to play TV audio to grouped rooms that are located in the same physical room in the Home.
Just to conclude though, there are some tools/features in the Sonos App that relate to grouped-room TV and line-in audio playback, that work to try to bring the TV/Line-in audio in sync across a group (called TV Dialog Sync) and to keep the audio playing to grouped rooms where there are network interference, or bandwidth, issues (called Group Audio Delay). You can read more about these tools/features in the following Sonos Support Links:
TV Dialog Sync
Group Audio Delay
I hope that the above information and the features mentioned, may help you to get your chosen audio sources playing reliably and in sync across your chosen Sonos & non-Sonos devices.
Thanks @Ken_Griffiths! That leads me to a couple questions:
- If the HDMI on the Amp is HDMI-ARC only, is it even possible to make that work when the receiver is driving everything? If I had something like, say, a Marantz Cinema 70s that has multiple HDMI outs including eArc, would that work? eArc to the Amp, regular HDMI out to my TV?
- Even if it could work, are you saying that once I introduce multiple Amp’s into the equation, it won’t matter anyways since a 75ms delay is effectively required for buffering between devices?
Thanks @Ken_Griffiths! That leads me to a couple questions:
- If the HDMI on the Amp is HDMI-ARC only, is it even possible to make that work when the receiver is driving everything? If I had something like, say, a Marantz Cinema 70s that has multiple HDMI outs including eArc, would that work? eArc to the Amp, regular HDMI out to my TV?
The Amp can be connected to a device-input that is either HDMI-ARC, or HDMI-eARC (the latter is usually backward compatible by switching it to ARC only in the sending device settings. A ‘regular’ HDMI connection (without an audio return channel) is not ‘directly’ supported, but 3rd-party devices can help to get around that connection (HDFury Arcana being one example of many) - Also Sonos sell an Optical to HDMI-ARC adapter that allows a sending devices optical-port connection to be used instead of HDMI-ARC - note the adapter is supplied/packaged with Sonos Soundbars, but unfortunately not with their Amp, so it has to be purchased separately (if required). It’s available here at Sonos.com:
https://www.sonos.com/en-us/shop/optical-audio-adapter
- Even if it could work, are you saying that once I introduce multiple Amp’s into the equation, it won’t matter anyways since a 75ms delay is effectively required for buffering between devices?
Yes, for line-in audio, or audio playback across ‘grouped’ Sonos rooms, but there is no delay to the Amp room (including it’s bonded surrounds/Sub) when TV audio is delivered to the Amp over its HDMI-ARC port. You can of course buffer the TV audio received (using the ‘TV Dialog Sync’ feature in the Sonos App) so that the Amp room (including its bonded surrounds/sub) play in sync with any rooms that you ‘group’ to the Amp, but note if doing that with TV audio, it will (highly likely) not be in lip-sync with the video on screen. Depending on the buffer size set/network conditions etc. - some people may hardly notice the lip-sync issue - personally speaking, I notice it.
It’s sometimes a case of just simply trying these things to see what you think about any buffer-delay introduced. Having 3rd-party Receivers/Amps in the mix can create further complexity that you may have to deal with too. As mentioned it’s sometimes a case of trying these things to see what you can achieve with your hardware and network environment.
Hope that info. assists too. 
You can of course buffer the TV audio received (using the ‘TV Dialog Sync’ feature in the Sonos App)
Yea, unfortunately that won’t work with my speakers that are powered by the Marantz. They’re already ahead of the Sonos, and from what I can tell, the “TV Dialog Sync” only works if the opposite is true. I tinkered with it but it didn’t help.
At this point it probably makes the most sense for me to return the Amp’s and to instead go with something like this: https://www.vssl.com/collections/all/products/vssl-a-3x.
It’s kind of hard for Sonos to play the signal before it has been received. I’m pretty sure they haven’t developed time travel yet. ;)
It’s kind of hard for Sonos to play the signal before it has been received. I’m pretty sure they haven’t developed time travel yet. ;)
I’m not sure what you mean. The problem isn’t the Sonos receiving the signal delayed, because it’s not. There is no delay in the analog signal coming out of the receiver and the analog signal received by the Amp. The problem is how long they take to do A2D conversion, bridge it with other Sonos, etc. For reference, I have 3x cheapo Aiyima amps that work just fine with this setup, but they don’t allow me to Airplay to each room individually.
It seemed like you were asking to ‘advance’ the Sonos playback, rather than delay it. Sonos does take a millisecond or three to process the signal, but it’s nothing at all like the 75 Ms that happens between the home theater room and any grouped rooms, where Sonos buffers substantially so the signal can be played in sync in all grouped rooms…something they also do with all analog inputs.
I have a Marantz NR1604 with B&W 5.1 setup in my living room. I also have a pair of B&W M1’s in my kitchen, bedroom, and office all wired back to the receiver. Each room was previously connected to the receiver pre-out with an Aiyima A07 amp.
I wanted something a little higher grade that would also allow me to AirPlay to an individual room with ease, so I picked up 3 Sonos Amp’s.
From what I can understand of the set up above, the Sonos based solution would be to wire a Sonos Port to any line in jack on the Marantz. And get as many Sonos amps as there are M1 speaker pairs that need amplified speaker level signals to drive them.
When all Sonos units are grouped together, they will put out a signal that is in perfect sync. You may then have to set the Marantz in stereo direct mode, to overcome the delay the Marantz will probably introduce in 5.1 mode. Once you set the Marantz to stereo direct, music from all speakers supplied via the Port and Sonos Amps will be in perfect sync.
