The Clear Audio+ feature on the Xperia Z3 automatically set the equalizer to deliver a unique and crystal clear sound. But to manually adjust equalizer on Xperia Z3, you need to do as follows:
1. Open Music app on your Xperia Z3 (Music is the new name for the Walkman application)
2. Tap the 3line icon on the top left, and then head to the Settings.
3. Go to Sound Effects and make sure the ClearAduio+ option is unmarked
4. Tap the Sound effects option, followed by the Equalizer option
5. You can create your own custom set or select from available sets, like Jazz, Treble boost...