Why is there input delay on line-in and digital inputs?

I don’t fully agree with @John B’s take on this. Yes, Sonos original was designed for local library playback primary, and then streaming services when they started becoming available, but I don’t think they were fully trying to discourage use of aux input sources.  Well maybe they were, but the reason is a bit more complicated maybe.

I think that Sonos sees the user experience as very important as a means of advertising.  They want customers to use their products as intended, a multiroom audio system.  If a customer buys Sonos and essentially uses as just a PA speaker, they won’t see the point of buying additional Sonos speakers when they have the need for more speakers.  Perhaps worse, other people who visit your home and see Sonos used as a PA speaker will not be impressed.  I see it as the same reason why Sonos took so long to add bluetooth to some options.  It’s not that they couldn’t, but that they wanted to control the user experience and the products used for the intended purpose.  We still see people who buy Sonos portables and use them just for bluetooth.  Or Apple folks who use them for airplay only.  And even folks who use Amps/ports only connected to Echos.  It doesn’t display the full potential of Sonos.

But that’s my theory, and I get why people would want Sonos to just be as flexible as possible.

Also worth noting that if Sonos had this standalone mode, you could more easily integrate Sonos speakers with other brands for your whole home system.  You could theoritically use an RCA splitter to make a system with a Sonos Five, third party receiver, a PA speaker, anything else that plays audio without delay from a single RCA source.  Sounds great, but doesn’t build out the Sonos brand.  Sonos took a hint from Apple about walled gardens.

I see them more as dirt path off the shoulder that people want Sonos to pave over.  Maybe they should, but it certainly wasn’t part of the original design.

I don’t think I was suggesting there was or is any attempt to discourage use of aux input sources, just that Sonos saw it as a marketing necessity to accommodate such sources.  On further reflection I am not sure I was right to suggest that if launching today Sonos would not bother with line in - but that is a hypothetical to which we will never know the answer.  

But it is still there almost entirely for its original purpose - to allow physical music media to be played across a multiroom system.

@melvimbe I actually used to have a Chromecast audio hooked up to my Play 5’s so I could cast youtube audio and cast from Google Chrome. Creating a Frankenstein audio system has always been possible since Airplay and chromecast etc became available.

Anyhow, like you guys say; it’s a decision that is  platform/experience/marketing oriented. A solution for people like me is to switch to Denon or buy a hybrid amplifier from NAD and extend it with a Bluesound module, etc… 

I just hope this thread is another reason for Sonos to consider standalone mode for Sonos Five and Sonos Amp. 

@Martech - I do get why you want this.  I just think you are destined for disappointment.  But who knows?

I have just registered the fact that you also mention digital inputs.  The delays here should be smaller than for analog inputs - to the point of being unnoticeable.  Has that not been your experience?

As far as I know there will always be a minimum of 50-75ms delay. Correct me if i’m wrong. HDMI is supposed to negotiate with your television to achieve ‘lip-sync). And I must admit, it took me a few days to get used to ‘lip-sync grade delay’. In the beginning I would notice, but after some time I didn’t bother anymore. 

But for live instruments (keyboard, drum machine) where you have to time your input based on the sound, a delay of 50ms+ is to high. 

For the Beam / Arc the delay should be of the order of 30-35ms.  Delivery to the speaker is effectively instantaneous.  The 30-35ms is to allow for surrounds to sync - even if there are no surrounds! - while being small enough for no noticeable lip sync issues.

This is why if you group another room to a HT room you get an echo effect for TV sound - it’s the difference between the delay within the HT room and the room grouping delay.

But I assume that for your purposes you have tried it and it is still too much?

When you are using a musical instrument are you still sending the audio through the TV?  

First of all, thanks for your help and thinking with me. 

No, I have not tried this. I actually sold my Sonos Amp only to read a few days later that digital inputs are supposed  to be faster than analog. But I did read mixed experiences about this on this forum and Reddit. Also I owned a Sonos Beam where I also noticed the lip-sync ‘issue’. The lip-sync was not to bad, but sold that one because I did not like the sound and bought the Amp instead.  
 

If anyone has input on this, and also on the Five ‘trick’ that @Kumar mentioned, that’d be great. Currently I only own sonos One’s because I had to buy other speakers for my usecase. 

Lip sync problems experienced with Sonos are almost invariably (possibly scrap the ‘almost’) by the timing of the audio feed from the TV versus the video.  It has nothing to do with Sonos.  Many of us have completely eliminated detectable lip sync issues by by-passing the TV for audio.  This requires an audio device like an HDFury Arcana.   Cheaper options do exist but I can never remember what they are.

The Beam / Arc will still introduce the 30-35ms delay and that might still be too much for your use case.

This is all a bit academic for you now!

Sorry - thinking as I go…

I suspect that if you had an electric piano or drum machine with optical out (if such exist) and ran it direct to a Playbar / Playbase / Ray (or Beam / Arc with supplied adapter) this might give an acceptable result.  Don’t know though!  Anyone out there doing that?