You need a Sonos Amp to power the two surround speakers. You will then add/bond the Amp as surrounds to the Arc in the Sonos app. The Arc/Sub/Amp setup will give you a 5.1.2 home theater setup. But unfortunately the Marantz and two front speakers cannot be included in this setup. Also, the Arc cannot be used as a center channel speaker.
If you want the Marantz and two front speakers to be included in your Sonos ecosystem, you can connect a Sonos Port to the Marantz. This would allow you to group all your speakers together when playing music.
Thank you @GuitarSuperstar for your response.
I’m not sure I quite understand the last paragraph. If I buy a port ONLY, would that allow me to use the front and the effect speakers in 5.1? I’m not clear what I need to do to use all four non-powered speakers.
Thank you @GuitarSuperstar for your response.
I’m not sure I quite understand the last paragraph. If I buy a port ONLY, would that allow me to use the front and the effect speakers in 5.1? I’m not clear what I need to do to use all four non-powered speakers.
There is no way to use separate speakers, Sonos or otherwise, as front left/right with an Arc or Beam as center. The Arc and Beam are soundbars, which include the left/center/right speakers in a single unit.