Sony might not boast about it, but the Xperia Z2 is among the selected few handsets on the market that feature front-facing stereo speakers. The speakers are plenty loud, though they cannot match the BoomSound speakers of the HTC One M8 in terms of quality. However, for some strange reason, Sony only uses the bottom speaker on the Z2 for incoming call notifications or when you’re on a call and using the speakerphone, which makes the volume barely audible.
Now, a developer over at XDA forums has released some modified system files for the Z2 that not only boost the speakerphone and earphones volume, but also routes the audio via both speakers. This means that users should hear the incoming call notifications from both speakers as well as enjoy higher volume output when using the speakerphone for calls.
The developer is also offering another flavour of the mod without the headphone volume boost, in case you are satisfied with the stock audio levels. He is also working on updating the mod with increased speaker output, which should please many Z2 owners. Make sure to keep your eye on the XDA thread if you are interested in it.
Installing the mod requires users to have an unlocked bootloader and root access on their Z2 along with a custom recovery installed. Head over to the XDA thread below for the download link.[Via XDA]