Itunes Soundcheck won't turn off properly??

Itunes Soundcheck won't turn off properly??

I have an iPod touch version 6.0.1 (10A523). I turned the soundcheck on to see what would happen. I didn't like how the volume goes quiet & the music quality goes lower....so I turned soundcheck OFF. However, I synced the music again with the box unchecked, but the music STILL sounds...bad & quiet! :/ :(

Can someone PLEEEASE tell me how I can reset all music settings back to *normal* like how they were *before* I used 'sound check?' Because it has ruined my music! (For now) :/