Is it possible to set the left/right audio balance?

Kodi apparently does not have the ability to set the balance, so I searched for a way to do it on the OS level (I’m no Linux guru), and found a suggested way with

amixer sset Master 80%,20%

but I get back ‘amixer: Unable to find simple control ‘Master’,0’

My audio is going out the HDMI to my TV and out my TV to my old set of speakers with their own control box that doesn’t have left/right balance and setting the balance on the TV does nothing.

Is there any way I can control the left/right balance using Coreelec?

This is on an Odroid C4.