Is the Sonos the soundbar he’s using? They don’t have a line in alright.
Two ways.
1. Use this Sonos instead. Has a line in and will let him also wirelessly send vinyl to the soundbar and any other Sonos speakers around the house.
Experience clear, room-filling sound with Sonos Five. Five's unrivalled acoustic technology delivers deep bass and impressive stereo for music streaming, vinyl and more. The stylish design features new details and a monochromatic finish. Enjoy control with the app and Apple AirPlay 2.
www.sonos.com
2. Use one of these. Won’t act as a speaker but feed the turntable into its input and it will again allow its sound to be wirelessly passed to the soundbar and any other Sonos speakers.
Introducing Port: the versatile streaming stereo upgrade from Sonos. Enjoy streaming music, podcasts, audiobooks, and internet radio on your existing stereo over WiFi with just one simple connection. Control your audio with Sonos app or Apple AirPlay 2, and easily expand your system to more rooms.
www.sonos.com
Also bear in mind that neither the fluance tables or any Sonos speakers have a phono stage built in so you’ll also need to get one of them.