Era 100 Line-In Question, Single Speaker Delay?

@tatoj 

The important question is… „a delay between what“. As you said a computer and other sources are mentioned as possible AUDIO sources. So using the pc as an audio source won’t be a problem though there’s the 75ms delay between input and output caused by AD converting. 
Stereo partners or grouped rooms always will play synced. 
BUT if you use the pc as an video source, there will be a delay between video and audio output. Besides this is the only reason because Sonos analogue input isn’t recommended for tv even if it just outputs stereo. 

Analog to Digital isn’t really the reason for the delay.  it’s the buffering need to keep wireless speakers in a multiroom audio setup in sync.

It‘s both… the minimum delay of 75ms that always exists is caused by the AD convertion and a minimum of buffering. If you use the „audio delay in groups“ option, the buffering time will increase. On top there could be a delay up to 2 seconds, if audio compression is active set manually or automatically. 
So IF analogue input is the only option for video content, you have to deactivate audio compression and set audio delay for groups to minimum. Maybe the 75ms are ok for some users. 
Really no delay as with Sonos HC products only can be achieved by using digital input (means no AD converting) and using no buffering. 
The missing buffering for digital input that produces an echo on grouped rooms can be eliminated by using „tv dialogue sync“. Imho this option produces a minimal buffering. 
 

No, it’s not both.  The delay is for buffering and buffering only, and is necessary for syncing between rooms.  The AD conversion is instantaneous.  

@jgatie 

This was my information from Sonos stuff… i don’t know how much of the 75ms is buffering or converting, but imho there must be some part of this time for converting because every technical documentation i found says that it can’t be done without minimum delay. 
But however it’s called… important to know is that for analogue input there is this minimum delay and that it has an effect on video sources and for using classic hifi amps bonded with speakers if they are integrated to a Sonos system via Sonos port or connect without using a pre out connection. 
But that’s a different story… 😉

I agree that buffering may be the bigger part of the delay. 

I don’t know where you got that info from (“Sonos stuff”) but it is not correct.  The delay has nothing to do with analog to digital conversion, it is for buffering only.  Also, the TV input has minimum delay because it is used exclusively to send the sub/surrounds signal over a dedicated one-way 5 GHz connection to a sub and/or speakers in the same room.  This connection cannot be used for music because grouped rooms can be anywhere in the home and the signal must pass through walls and floors to get there.  Since the low latency 5 GHz signal isn’t strong enough to pass through walls/floors, music is transmitted between rooms via the buffered 2.4 GHz connection.

Yea I’m worried about lip sync issues.  My computer is a multi use device, and while sometimes it’s music where lip sync doesn’t matter, other times it’s youtube or netflix where a lip sync issue will be a problem.  That’s why I mentioned since they have specifically listed computer as a Line-In feature now, I wasn’t sure if anything was different with the ERAs.

That’s why I was curious if a single 100 (not in a wireless pair, not grouped to other rooms) would be even lower than 75m since there’s nothing to buffer/sync up to, just direct audio to one speaker.

From Sonos:

A quick note on Play:5, Five, Connect:Amp, Port, Connect, Era 100 & Era 300

While it is possible to use these players with a PC by connecting to their line-in ports (Era models will need the USB-C adaptor), this isn’t a recommended solution if you’re planning on doing something that requires audio/video synchronization. There will be a minimum of a 75ms delay on the audio due to the signal processing performed on the line-in side. If synchronization isn’t an issue for you, you can simply connect the device to your PCs headphone or line out jack like you would a pair of regular headphones.

There’s no such thing as a “single 100”, because at any time a “single 100” can become a “grouped 100”, which would require a buffer.  There’s no way for a single 100 which is not buffering input to become a grouped 100 which is buffering input, unless the audio is stopped in order to build up the buffer.  Audio stoppages when grouping are not good for business, especially for something sold as a multi-room music system, so the buffer is there, single use or not.