[Feature Request] Mono mode

[ProgrammierPatrick]

First of all, thank you for this great application!

A nice addition would be a toggle which can mix the stereo down to mono.

I regularly listen to music with just one ear if I need to hear my surroundings. Sometimes instruments are panned hard left or hard right in music (e.g. in old Beatles albums). Then you can not hear some instruments. It would be nice if one could just toggle some setting in the app and get a mono downmix.

[bhatiak2050]

I would also like this to use this feature in the app.