Balance left/right speakers

I have volumio on a RPi3, with Hifiberry Digi+ and a digital amplifier. The Digi+ has no volume controls (hardware or software, as far as I can tell), and the amplifier has only a volume knob, but no left/right balance.

Is it possible to control the balance on the software level? I’ve tried installing the ALSA equalizer plugin, which could be somewhat abused for balance, but I can’t get it to work with mpd (see other topic). Could I maybe add another ALSA control only for balance (and I guess I’d have the same problem with mpd)?

OK, if I enable software mixer I get an ALSA control I can modify, where I can control left and right channels. Any touch to the Volumio volume sets balance to center, but that may be good. I can configure a remote button to do:

amixer -c 1 sset SoftMaster 87%,100%

for my off-center sitting position, and then I can just push vol+ to set balance to center and volume to 100%, so I can easily toggle between both settings.

Does the software mixer significantly affect the quality if left at 100%?