Neither should create any latency, from the perspective of the Sonos’ connection to the LG. If there would be any difference, it would be in the PC.
Sonos has zero idea about what is feeding the signal to the TV, all it knows is what it is receiving. It does tell the TV, via CEC, what kind of device it is, and what formats it can deal with, but it is up to the computer in the TV set to deal with that, and pass it to any other devices.
Thanks. There was a very noticeable delay when using “Dolby Atmos for home theater” mode on Windows 10. However I did find a fix that resolved this. For audio output i had to put my TV (LG C2) in passthrough mode and restart PC/TV. No more latency issues.
I had one other issue I wanted to resolve too. When watching something like Youtube and then pausing the video for a short time it would put the SB into sleep mode and when I pressed play again it would play with no audio for a good 1 or 2 seconds. I found an app called Sound Keeper that stops SB from going to sleep. Works perfect.
I wanted to mention this incase anyone else runs into this issue.