Depends on the generation of the Connect.

How do I determine that?

If it’s on your system, you can go here:

https://www.sonos.com/myaccount/system/households/devices/

Log in and see if it says “Sonos S1 Only” next to the Connect.

If it’s not on your system, look at the first four numbers of the serial number.  They are the YYMM of manufacture.  Anything 1503 and over is Gen 2 and will be S2 compatible.

Thanks, I’ll check it out.

What function is the Connect playing in what you want to do?  What source(s) do you want to play?

I usually play a local radio station or something from Pandora.

Two questions.

1. why wouldn’t you use the Line in on the PLAY:5, instead of on some other device?
2. Why wouldn’t you just use Sonos to connect to either Pandora or any of the various radio carrying streamers, and skip the use of the line in completely?

I have been using the S1 controller for a Play:5, a Move and a Connect for a small stereo system. I just bought a Roam SL , which doesn’t work on the S1 app. The Play:5 doesn’t work on the S2 app. I like the sound on the Play:5, so I would like to use the Connect to run the Play:5. It does work on the S1 app so hopefully it will work on the S2 app when I get a chance to switch over the speakers to S2. 

The Connect will work on S2 if it is gen 2, but not if it is gen 1.

If your proposed set up does work, the sound from the Connect/Play:5 combination will not sync with the Move, and so I cannot see much advantage over just leaving the Play:5 on S1.

You are correct. I can get the Play:5 to play using the Connect, but there is a short delay compared to the Move. Since I use them together, that is not practical. Back to the S1 app.