Perhaps see this YT video…

https://youtu.be/w93asIB3qFM

When playing music, you can set the audio output to ‘Full’ and it will play on ALL speakers at/upto 24bit/48kHz UltraHD/Atmos audio quality.

Music is great, if you're listening to Dolby 2.0 TV they are nigh on redundant.

Try the Fives as Surrounds as you already have them but think about the rest of this.

I’d be tempted to keep the Fives as a front stereo pair just for music. Alone for the most part but you could Group in the Arc and Surrounds (in Full Mode) for party music.

Hook the Arc to the TV and add some One SLs as surrounds. The SLs are plenty for TV Surrounds. The Fives would work there and sound good for party music / Full Mode but are overkill for Surround audio use.

If you get a Sub I’d consider hooking it to the Arc but you can move it back and forth and pick your favorite. Maybe even buy a second (third or fourth if you are rich) Sub.

Jeez, 2 Fives being used for surround seems like a waste. I’m sure they’d be great but it’s total overkill, a pair of One/OneSL work fine for surround. Agree with Stanley, keep the Fives for music.

I sure wish Sonos would allow us to use other speakers (Fives, Ones) as front L+R in a 5.1 system. My home theater is anchored by a Playbase, which sonically and stylistically is terrific, but doesn’t have an immense front sound field. Yeah, I know an Arc is somewhat wider, but it’d be nice to have dedicated front L/R that we could place wherever we want, and let the Playbase/Playbar/Beam/Ray concentrate on center channel duties.

Obviously, it’s personal, but I like FIVE’s for surround -- especially for the chase scenes. For a few crickets worth of ambience, ONE’s are probably OK.