Got my first Sonos One from Amazon Prime Day and I was excited to try out streaming my PC audio via Airplay...but Airfoil apparently cannot connect to Sonos right now, asking for a non-existing password.
So I ended up using a wacky workaround:
0. Have an iDevice
1. Connect to One via Airplay on iDevice
2. Get Airfoil Satellite on iDevice
3. Send PC audio via Airfoil to iDevice
4. iDevice plays audio to One
It does seem to have add some latency, and will apparently gobble up your wifi, but at least now Airfoil works.
Discuss if you have a better way