OSMC and audio mixer? Faint volume via Line out

I’ve got a problem with my RPI 2 and the osmc RC.
I’m currently using OSMC “headless” mainly as an audio player connected via the line out plug to the aux in of my stereo.
I noticed that the volume from the Pi is quite a bit lower than when I switch to FM radio or CD on my stereo. So I was looking for the mixer app on the console to boost the volume to 100% to what I remember was 89% on Kodi before.

However amixer or alsamixer do not seem to be used anymore with osmc? Also after installing the alsa-utils package the tools cannot find the proper devices.

How can I change the volume of the line out on my Pi from the command line?
Thank you!

I’ve got the same problem: I want to use the OSMC as an AirPlay receiver for my stereo, but the sound over the audio jack is very low compared to the headphone jacks on all other audio players I own – even when I turn OSMC up to “100%”. Plus, the sound seems to lack certain frequencies (?).

When I tested RaspBMC (installed via NOOBS) on the same Raspberry Pi, this problem did not exist.

Is there a fix for this? (I’m using a Raspberry Pi 1 Model B.)