Starting out using the Port

Not speaker outputs, those are amplified.  The Line-In takes a line level input, something you get from RCA outputs on your tuner. 

Most often, people tend to use tape outs, if your receiver has them. Easiest to think of the Sonos Port or the older CONNECT as a tape player. 
 

It’s sometimes more difficult or even impossible on newer devices that don’t provide a line level output. Depends on the ‘amplifier’ in use. 

Well, the Tape Out is not an RCA connector. So it looks like I need an AUX to RCA adapter for my 2 yr old  SONY tuner

What is the model number of your SONY unit?

AUX to RCA adapter? RCA is indeed a form of a connector, but AUX is a source. I agree with ​@buzz , please provide the model of the tuner/receiver.

Sony receiver model STR-DH190

Using the Port is a great way to send streaming music to your Sony and send music from a turntable or CD player to a Sonos speaker. 

The question you should answer for yourself is:

• How long do you intend to keep the Sony in the mix
• Is steaming music to the Sony and its speakers a high priority (which can be done with the Port)
• Do you have a turntable or CD player attached to the Sony that you would want to send the audio to a Sonos speaker(s) via the Port

Your cost for a Sonos Port is $499_USD. Adding a Sonos Era 100 to start your Sonos speaker setup is $199_USD (normal retail). Therefore, your entry cost to Sonos is $698_USD

On the other hand, two (2) Era 100’s are only $398_USD. That’s either a savings of $101_USD (Port Only) or $300_USD (Port and Era 100) respectively.

Not trying to say one option is better than the other. Just want you to consider your initial investment cost and your perceived audio enjoyment over the short and long term.

I hope this helps you to make an informed decision.

There doesn’t seem to be a better way to listen to NPR music than this, and it does provide a way to listen to CDs and the turntable as well.