No - if you connect from speaker outputs you will overload the input on the Port. The Port has one analogue input, and it is a “line level” input - it needs just a few volts maximum. So you need a line-level output from the receiver - sometimes described as “pre-out”.

If you say what make/model of receiver, someone here may be able to look up the details and advise on what options you have.

Also sometimes known as a ‘tape loop’. If your receiver has it, you can connect the Sonos Port to the Tape Out / In. Out in the receiver to in on the Port, in on the receiver to out on the Port. It works essentially like connecting a tape machine. 

If you tell us what receiver you own, we could point you to the right connections.