What are your speakers wired to? If there is a power amp or receiver powering them, you can use a Port to stream music through them and the Sonos speakers. 

If you do not already have anything to power the speakers, you can use a Sonos Amp that can be grouped with other Sonos speakers.

My wired speakers are connected to a receiver, so using a Sonos Port sounds like a great option to integrate them with the Sonos system. I’ll look into that setup. The Sonos Amp also seems like a solid choice if I need to power additional speakers in the future.