My headphone output suddenly and strangely weakened by half

I was playing yesterday geometry dash with my headphones (because the music is so good!) on my Samsung galaxy s3 mini value edition (i8200) and suddenly, without any interaction, the music weakened by half - but the output, so when I press vol+, hasn't changed. Therefore when my volume is maximum, I can scarcely hear the music. That's the first time. What I tried: * rebooting. Didn't change anything * removing almost all xposed module. * changing volume steps from 15 to 30 in gravitybox I have rooted the device and my superuser app are Kinguser and SuperUser. Help me please :)