You do not need to have the TV powered on… the Ports ‘line-in’ where your Amp/TT are connected to, shows as a music source in the Sonos App ‘Browse’ tab below your music services - it can be selected to play the line-in audio to any speaker, or group of speakers, in the App. See screenshot attached.

There are also options to ‘Autoplay’ the line-in audio at a preset volume etc to your chosen room(s), this is available via the Port ‘room’ settings in ‘Settings/System/ Port Room Name]’.

Right now the only Sonos product I have is the Playbase. I’ve been thinking about adding a pair of ones. Using the port with line-in and the ones and the playbase as speakers will the turntable be able to play through all three? Will it be stereo out of the ones?

Yes….if you have the Ones set up as a stereo pair. If they’re set up as surrounds for the PLAYBASE, you’d want to set them as ‘full’ playback in the music area of the surround settings on that room. ‘Ambient’ wouldn’t necessarily be full stereo.

You can assign play back of the line in on the Port to be any room you choose, and you can always group rooms. 

I’ve been reading a bunch of stuff here about stereo vs surround. I’ve never set up a surround system. If I have the play base and two Ones is that a 3.1 surround? 2.1? My inclination having grown up with analog stereo equipment is that the ones should be set up in front as stereo speakers, but I take it the more common configuration is to use the ones as rear speakers. What is the playbase providing in a surround setup with the ones as rear speakers? A center channel and a front left and right?

It would be 5.0.  Left-Center-Right in the Playbase, 2 surrounds, and no subwoofer channel.

 My port has arrived, and I’m not sure what to connect to what. Attached is a photo of the back of the amp. I thought there would be a line-out on there but I don’t see one. I assume I should connect the turntable to the phono inputs on the amp, but what output do I connect to the port? I’m not using any passive speakers. I am basically using the amp as a pre-amp, and want to send the audio to my playbase.

It is best to use the Tape 1 connection for the Port. This has an “In” and an “Out”, which you would connect to the “Out” and the “In” on the Port.

Tried turntable into into tape 1 and from tape one out to port. Nothing. 

Turn the Tape Monitor setting to On on the receiver.  Also, try setting the Port volume to fixed.

I meant you need to connect the Port to the Tape 1. Turntable needs to be connected to Phono.

How can the TT signal get to the port then? 

It would travel the same path as if the Port was a tape machine, as if you were recording a vinyl  to tape. In this case, rather than going to the tape, it is sent to the line in on the Sonos, processed, and broadcast to all grouped Sonos devices.