I've just repurposed two Play:1 speakers to act as rear speakers in a surround sound TV setup. I have a Beam connected to my LG TV via HDMI ARC which seems to work fine, receiving Dolby Digital 5.1 from the TV.
The first problem I faced was getting both Play:1 speakers connected. For a long time they refused to connect as surround speakers, with the setup routine failing with a non-descript error message ("failed to connect" or similar). After resetting both speakers to factory settings, they eventually connected and the app shows them as "Play:1 (Left)" and "Play:1 (Right)". So far so good!
Unfortunately I'm still not getting full surround sound since the left speaker stays completely silent, whether watching TV or playing music from Spotify. It successfully controls TV audio (e.g. for volume adjustment) but it's not playing any sound. The Beam and the right speaker are both working fine.
Suspecting a latency issue, I re-installed an old Sonos Bridge and restarted all my speakers to get them working in "Boost" mode and eliminate any home Wi-Fi problems (I have a mesh with multiple access points). Still no sound from the left speaker!
I'm not getting any error messages and everything appears normal in the "S1" controller app. TV Level and Music Level are both turned up to full (+15) in Surround Audio, with Music Playback set to "Full".
My next step will be to throw the bloody thing through the window, but before I try that does anyone have any other ideas?