Try with stock Rom then and tell me, back up your current rom and flash stock over itI'm on stock based Poison v2.2 android 7.0 https://xdaforums.com/xperia-x/development/romubxperia-poison-v1-0-xx-f5121-5122-t3525884
And previously (v7) didn't have any issues with the SoundEnhancements apk.
Thanks!