Xperia Z3 Plus, Inconsistent Media Volume or Auto Optimization

[Sylus]

Hello

Bought this extremely awesome phone which is good in every aspects except the Speaker. While playing Music with Sony's own app or watching any video, the sound (tone) changes.To restore the perfect tone I need to stop the music, remove from recent apps, open it again and its restored for maybe 10 secs(very inconsistent timing) and back to same distorted tone. I've tried clearing data, repairing, taking it service center and still no fix.Service center executives refuse to believe that such problems exists. My only Question is If this is a Hardware issue or a software bug. And no water contact has been made till date. I'm not sure but I think the problem was also on Lollipop. Love this phone though! 

Thankyou

[Sylus]

Yes I used another device and not the inbuilt mic because both the speaker and mic lie on the same place and the difference was much less noticeable when Screen Record is done. And all the settings were kept the same.

[Rickard]

@Sylus

I'm afraid this seems to be hardware related. I recommend that you contact your Local support or a service centre for assistance in this case.

[Sylus]

That's one of the first things I did and the answer I received from multiple executives are as follows. Don't use a third party app (referring to YouTube but also happens on Sony's own music app), Everything is fine Sir you ain't hearing it right, use headphones instead. It's is a software issue and will be fixed. Stubborn.

[Sylus]

Updated to 32.2.A.0.224, factory reset done, repaired the phone and still no fix. This is what i get for investing my love in Sony!