You’re going to need to ‘feel stupid’ to connect both a TV and an LP to a Sonos system, unless you connect your LP to your TV. For better or worse, that’s the way Sonos is designed.

Alternately, you could rip/digitize all your music, and place it on a hard drive/NAS, and let Sonos read it from there. Then you wouldn’t need to ‘feel stupid’ and buy a separate Sonos device to connect an LP. 

The least expensive way to get music from a turntable into a Sonos ecosystem is using an Era 100 with the Sonos USB-C adapter. This will cost you less than a Port would cost you.

Thank you for the replies. If I would purchase the Sonos era 100, would this set up be ideal?

• Connect my pre-amp (connected to my turntable) to era 100 with line-in adapter.
• Connect the era 100 to the Arc through the Sonos app

If this is the case, I could play vinyls through both the era 100 and Arc? And when watching Tv, the sound would also be passed through the era 100 and Arc, right? 
 

If this is the way to go, could I switch between listening to vinyls and watching Tv with ease? And how do you recommend placing the era 100 with the arc? Obviously one era 100 is not sufficient for surround. Or would the best option be to use the era 100 only for the vinyl and not linke it to the arc at all? 

I don’t recommend attempting to listen to TV audio through 100’s because there will be a slight audio time offset that flusters most viewers. Viewers will feel that lip sync is skewed and there seems to be an echo.

There will be time alignment when simultaneously listening to music on ARC and 100’s.

You are using the word "link”, that is not part of the Sonos lingo. With Sonos, you can “group”, "pair” or “bond” speakers. All are different forms of what you could mean with "link".

Using one Era 100 with your turntable will give the system (Era and Arc) access to a new source, Line in. Both the Era and the Arc wil be a 'room” in tyhe app. You can play Line in on any of the two "rooms”(speakers), or “group” the "rooms” to have them play the same music in sync. As ​@buzz says, this will be in sync for music but not for TV sound - with TV sound the Era will lag at least 75Ms behind.

Two Era speakers can be paired in a stereo pair. They wil form one "room” in the Sonos app, that can be grouped with the Arc. One or both Line in's can be used by the system. Same caveat when grouping with the Arc for TV sound.

You can also "bond” two Era's to the Arc as a surround set up, in which the Era's wil be the rear speakers. Unfortunately when bonded the line in on the Era's is disabled for technical reasons.