What happens if you wire the left speaker to the right speaker terminal and right speaker to the left speaker terminal on the Connect:Amp? Also try unplugging the TV and Connect:Amp from power for a couple of minutes.
@GuitarSuperstar - Done all that. Even with a new audio cable. Also tried all of this with another audio source (my phone).
I suspect the left input channel is faulty?!
If so, will this show in a diagnostics report?
Yes, I would imagine it would show the faulty left channel. Go ahead the submit the diagnostics and post the confirmation number on this thread.
https://support.sonos.com/s/article/141?language=en_US
Diagnostics sent. Confirmation number 1301773213.
Head smacking detail: Make sure that the L/R balance control is set in a reasonable range.
Also note that the Line-In detects if there is an RCA plug inserted. Some times, if the pin is short, this detection fails. As I recall, both Line-In’s need a plug before the controller will allow access to Line-In.
@buzz Line in is detected and available with cable connected to RCA right channel only. Also vith both channels connected but only sound in right speaker. Linie In not detected with only RCA left channel connected.
Are you able to play both channels from an online music source at your location? You have some sort of Internet connection if you are able to submit Diagnostics.
Unfortunately, the symptoms are converging on a left channel Line-In fail.
At this point I would be tempted to smack the unit very hard with an open hand. This is mostly a potential diagnostic trick. If there is a broken internal connection this sort of physical shock might result in a very temporary, fragile “repair”. The repair may last seconds, hours, days, or whatever.
In its present condition CONNECT:AMP has some value as a trade-in. If you are the DIY repair type, and my “smack” repair gets results, you may be able to find and repair the bad connection, but this connection could also be inside an integrated circuit and beyond your reach. SONOS does not support any sort of field repair.