Option to Produce Mono Input Signal to Drive HA Media Player

In my implementation, I am using Sonos Connect Amps with HA media players and Spotify for a music source. Due to the layout of the speakers, I don’t want stereo.

Instead, I would like to select the audio source (here, Spotify) and then indicate to make it source mono. Then, the hope is that the media player will drive this mono signal to the amplifier so it doesn’t know the difference.

Perhaps this can already be done – but I did not see anything in the community about it. Any thoughts on the proper direction on this?