Coolpad max music volume is to low

I suspect this is the case for serveral Coolpad models, not only E2

I think there is a connection between the fact that there are no system volume bar to alter

https://www.lifewire.com/thmb/qW2m9ixOSjWTX08x_rvfY9r3lSo=/2170x0/filters:no_upscale():max_bytes(150000):strip_icc():format(webp)/005_ways-to-improve-android-sound-volume-4174615-407eef7748b9433db1493086d5af8232.jpg

and that the MAX volume for playing music in headphones and earphonnes are to low for comfort.

Anyone else recognize this problem? i also strongly doubt its my headphone phone jack on my particular phone that causes this, and i have no chance to control that either.

Unfortently it doesnt work to boost the soundvolume with an Equalizer app or musicplayer either.

I have tested all this tip https://www.lifewire.com/ways-to-improve-android-sound-volume-4174615

and nothing helps. In case you have nothing to add im going to be forced to get ridd of Coolpad and assume this is Coolpad sound-level.

Any ideas?