The Arc setup is the better option. It is a 5.1.2 system that supports HDMI eARC and higher quality audio formats like Dolby Atmos, Dolby TrueHD, Multichannel PCM, and Dolby Digital Plus. The Amp setup is a 4.1 system that supports HDMI ARC and is limited to Dolby Digital and DTS Digital Surround audio.

With either option, once you have it set up correctly, you won’t have to do anything other than turn on the TV and everything will be good to go.

When streaming music in stereo to either system, the music will play from the front channels and surround channels in full stereo. Just make sure you have the Music Playback setting under the Surround Audio setting set to FULL. The only time the music will play as surround channels out of the rear speakers is if you are playing music mixed in 5.1 or Dolby Atmos (with Arc setup).

What model Sony TV do you have?

Extremely helpful, thank you!  TV is a XBR-85X900H and we like it mounted low, 3’ off the floor.  Wanting an electric fireplace underneath, so the in-wall speakers would fit cleaner, but the Arc is doable. I had read that the in-wall pair can simulate a Centre channel but you bring up a great point that I will never be able to run Atmos.

Me and the little ones also jam to tracks I play on my existing traditional 5.1 system so I would also like to do that with ease as well. 
 

The X900H is equipped with eARC so it will work well with the Sonos Arc setup.

Playing music through a Sonos system is extremely easy. You can stream directly through the Sonos app or from a third-party app like Spotify or Amazon Music. With an iOS device, you can also stream to your Sonos system using AirPlay. But the easiest way to play music to Sonos is using a voice assistant like Amazon Alexa, Google Assistant, or Sonos Voice Control.

With AMP or ARC up front and you ‘Bond’ the AMP driven ceiling speakers as surrounds, you will not be able to quickly pull the rears out of the surround system to be used as a stereo pair. It’s possible, of course, but this requires some fussing. SUB will be attached to the front speakers. It will require more fussing to reassign it to the rears while you use them as the only stereo speakers.

If the in-wall front speakers are relatively close to the TV, center channel is redundant. If they are some distance from the screen, or image poorly, you will usually experience a “hole in the middle” that would have been filled by ARC.

I don’t recommend attempting to “jam” through the SONOS system. Certainly, you can play tracks, but you’ll bump into latency issues if you attempt to incorporate a microphone. Note that ARC does not offer a Line-In. AMP has a Line-In, but Line-In is disabled when AMP is used as a surround amplifier.

I have older Connect amps which uses the S1. Looking forward to the S2 integration and features.

I have another setup question for living room. This room is open (with 20’ ceiling) with a kitchen behind it. I am mounting a TV but do not need surround sound so this may be a good application for amp plus wall speakers by the TV and then add “regular” non Sonos ceiling speakers near the kitchen.  Those speakers could easily dial up and down based on kitchen noise.  Could also use a soundbar here as well but it would be for fit and finish, not for surround.  Am I on the right path?

If I went with an amp, could the amp be downstairs in mechanical room or does it need to be in the same room?  I have experienced latency issues running 4K over king HDMI lengths. 

Check the temperature ratings of your Sony screen. The rating of 104F or 40C is really iffy for mounting over a fireplace.

Not here: https://www.sony.com/electronics/support/televisions-projectors-lcd-tvs-android-/xbr-85x900h/specifications

Page 12 here: https://www.sony.com/electronics/support/res/manuals/5014/e8c65254f0b9b4a85572b79ff905830e/50148591M.pdf

Operating temperature: 0 ºC – 40 ºC /
32 ºF – 104 ºF 

The latency that you are experiencing is not due to cable lengths, it is built into the SONOS system. This latency helps the system to work through network communication issues.

As long as the remotely located AMP has a good network connection you’ll be fine -- unless you attempt to connect the TV sound through AMP’s HDMI connection. In this case you’ll run into another set of latency issues. These issues can be somewhat mitigated with some clever adjustments, however, TV lip sync will be degraded when you do this.

Another detail that you may bump into if you have multiple TV’s in the room is that cable boxes and Internet feeds, such as Nerflix are not guaranteed to stay in sync while watching the same content.

There are a lot of moving parts here. It might be beneficial to consult with a pro.

@buzz how else can I connect the TV audio to the amp if not through HDMI input?  In this scenario/room I have no soundbar, only architectural speakers. My question was about remote mounting the amp(s) rather than having the one amp close to the tv. 

The issue is not with the exact physical location of the AMP’s or soundbars, its the various audio latencies. There is a 75ms processing latency between Grouped SONOS players and the source. There is a 30ms latency between its HDMI (or optical) input and output from a SONOS soundbar. If you use a Grouped, separate AMP to drive the kitchen speakers it will be in the 75ms bin. If you use the same AMP as the surround speakers, the kitchen will simply become a remote copy of the surround channel (eliminating the latency misalignment) and you could use separate Volume controls inserted in the speaker wiring and balance the output in order to deal with the kitchen noise. I don’t think anyone would enjoy this arrangement. When using a separate AMP for the kitchen, an option would be using the SONOS controller to tinker with the lip sync, adding additional delay for the TV’s HDMI or optical audio, aligning it with the 75ms Group latency.

Since latency issues drive you mad, consider the physics if the situation. Sound travel in air is rather pokey at about one foot per millisecond. Consider speaker ‘A’ and speaker ‘B’ separated by 30 feet, driven by the same amplifier. Audio in the wire travels near the speed of light in a vacuum. A listener standing near speaker ‘A’ will claim speaker ‘B’ is 30ms late. A listener standing near ‘B’ will claim ‘A’ is 30ms late and a listener standing at the midpoint will claim “no delay”. All three listeners will be correct. My point is that one must work with all of this such that the audio is aligned at the primary listening location.

@buzz you are in the big leagues!  I catch most of what you are laying down - thank you for taking the time to explain. If I have two in wall speakers in front, and two in ceiling speakers in the rear, I see my options being:

1. One sonos amp and 4 sonos sonance speakers. Can rely on true play to optimize. TV output to amp via hdmi or optical. Amp may be located at tv or 30 ft away downstairs, and system should self optimize. 
2. One sonos amp and 4 “regular speakers” with same setup as above. True play will not work with this config, but I will have manual settings to adjust zones if needed. 
3. One sonos amp with 2 sonance speakers up front, and find a spot for Sonos One to augment the sound level in the kitchen.

My objective this room is to have a strong TV sound with no lip sync issues in front of the tv. In the rear, I’m not as concerned with lip sync because I’m not close enough to the tv anyhow. I just want the sound to be fulsome. When playing music, obviously no lip sync to deal with. 

#1. You will have two sets of speakers attached to AMP. This will not be surround sound, you’ll have the same output from both pairs of speakers. You should have in-line speaker Volume controls to balance the levels. You’ll have the ‘A’/’B’ listener disagreement about delay, depending on listener location, but it will be on the order of 30ms and this may or may not matter to you. 30 feet between AMP and TV is not a big deal for audio. Use good quality cables. 

#2. Same comment as #1. I’m being a little pedantic, but I don’t think that you should consider the two sets of speakers as separate “zones”. We normally think of “zones” as being able to play separate content.

#3. The ONE(s) will be in the 75ms bin and AMP, if you use HDMI or Optical will be in the 30ms bin. If you use AMP’s Line-In for the TV audio, it will be in the 75ms bin. AMP and ONE(s) will be separate zones. In SONOS lingo you would “Group” the “Rooms” to play the same material and the Rooms would be time aligned with each other. (subject to the listener’s physical location, of course) When playing music AMP will always be in the 75ms bin.

Things are a bit slippery when using HDMI/Optical for the TV to AMP connection because there is an adjustment you can use to increase the latency to be very close to 75ms -- at the expense of lip sync.

#4. If you want true surround for the TV, you’ll need a second AMP for the rear speakers or you could use a pair of ONE’s or FIVE’s. Trueplay can tinker with things somewhat in an attempt to optimize the favorite TV viewing seat.

@buzz thanks I’m learning a lot here.  So all Sonos users simply need to deal with the 30ms latency at the source, which would typically be either a soundbar or an amp. This must not be very noticeable otherwise complaints would be widespread. Any grouped device (another amp or satellite pair of sonos speakers) adds another 75ms so they would be playing 105ms behind the tv picture.

For my application, it seems that using a single Amp with two pairs of standard in wall/ceiling speakers is the value point.  The single grouping will play at the same 30ms delay, and I doubt any listeners will detect a difference (I have this setup right now with older non sonos equipment). 
 

One thing that you have mentioned twice now and that is “if” I connect tv to Sonos device through HDMI or optical. In what other way would I connect?

No, you will not have a 105ms latency. If you are playing audio from an HDMI video source through a soundbar or AMP, the latency will be 30ms for those speakers. If you simultaneously Group another player with this source, all members of the Group will be time aligned at 75ms. Depending on which speaker you are near, the latency will be 30ms or 75ms. Unless you are able to simultaneously able to hear speakers from both audio chains, this difference is usually not significant -- unless you attempt to provide lip sync audio to a remote monitor via a Grouped player.

The latency is added by the SONOS network transport services as a hedge to allow recovery from network communication issues before there are audio consequences. Data over a network is sent in “packets”. If a packet is delayed or lost the audio will suffer unless there is enough time for the packet to be resent before the player runs out of data. For a soundbar there is typically no network connection  (wired or wireless) between the TV and the audio system. Plus, a long latency here would impact lip sync significantly. Because there may be network supported surround speakers and SUB’s, some latency is prudent, but since surround speakers are typically in the same room as the front speakers, reducing the latency to 30ms is relatively low risk. In most cases a private, local 5GHz connection is used between the front and surround speakers. This connection is not visible to a regular WiFi user.