No. In fact, I’d recommend against it, assuming the Arc and the Amp are within wireless (5Ghz) range. Saves an extra routing step when they communicate directly. 

Thanks. Just to confirm, you are saying it does not have to be hardwired and you would recommend against doing so if both are within range?

Wiring Sonos isn't normally needed and can complicate things. Best to skip it unless you have issues that need it.

Yes, that is what I am saying. Turning ‘off’ the WiFi on these devices, and forcing them to go through the extra step of communicating through the router itself is unnecessary. It adds potential (albeit extremely slight) delay. In some rare cases, that becomes problematic. The original design intent was for them to be wirelessly connected to each other. Why try to go against that?