I think quite literally everyone’s gripe is that the menu commands are excessive and annoying, not that the technology behind the swapping can be streamlined in some way that you aren’t privy to.. Why do a true play when you could just slide sliders? Why airplay when you can just line-in everything? Why bother with Sonos at all? Seen you arguing against this simplification on posts dating back to over a year ago. Does Sonos really want to “bring every room together” by requiring 5 rooms worth of speakers for 5 different functions in one room? 

As I read his post @jgatie is not disqualifying the idea behind the feature request. He is just pointing out that this would be very hard for Sonos to do seeing the way Sonos is set up right now - and that even an automated function would take a couple of minutes to happen every time a change is made.

And (but that is my criticism) all for a feature you would not ask for using a classic wired home cinema set up, and that would result in Sonos selling less speakers to people really wanting this option.

@106rallye
all for a feature you would not ask for using a classic wired home cinema set up

well not necessarily, the feature request here is because Sonos restricts a method which is intrinsic in a classic wired home cinema setup, hence the request. In a classic home cinema setup, you’d choose Phono/line on your amp/tuner/pre-amp and play it through your speakers in whatever config that model allows. In the case of Sonos disabling the line in for the surrounds is due to their architecture, the occasional request for some kind of feature to accommodate a line in to a system without doubling up speakers in the room shows up from customers. 

anyhow I guess this doesnt matter any longer, at least for me. I found my solution to the issue. In following post...

UPDATE: 
no direct solution regarding switching my living room speakers from surround setup to using just the Era100’s +sub as stereo so I can use the line in. 

Solution: 
After a few weeks of watching auctions and looking around online marketplaces, I bought a used Port off of eBay for $160.00, set up my Living Room in HT mode and set the living room as the autoplay room for the turntable line-in on the Port, they are in the same room. All seems to be working fine and the resulting audio sounds great for our needs. This gives me functionality I was ultimately looking for, albeit at a cost.

The Port shows up as a “room,” change the names to suit, ie; Room: Turntable. 

in “Turntable” room:  
Line-In: Source Name:Turntable
Line-In: Source Level: 7 (or to suit)
Line-In: Audio Delay: High (depending on network speeds or audio dropouts)
Line-In: Autoplay: Living Room (or room of choice)
Line-In: Autoplay: Include Grouped Rooms: checked
Line-In: Autoplay: Volume: Use Autoplay Volume: Checked, set at 30% (so you hear your music as soon as the track on the record starts)

in Living Room:
Surround Audio: Music Playback: Full. 
Spacial Music: off, (even though it’s nice on some music like jazz quartets when it’s on)

any other settings are to your personal taste or needs.

Worth noting if you find a used Port, factory reset the used unit you purchased and update all your firmware on all components before messing with functionality. My Port was not ingesting audio at first until I made sure everything was up to date after a factory reset, this may have included other components, so be advised it was not a plug and play device out of the box by any stretch and I was worried I might have bought a bum unit. 
System Settings: Manage (to the right of system name): System Updates: Check for Updates

A bonus to this $160 expense was that now my speakers will remain in HT mode for watching 5.1 movies and shows. The Port is expensive for what I need it to do, but this works and I found a good deal through patience. Good luck to the rest of you!