As title says, the problem happens in my notebook(not mentioned in system spec) which is an unmodified HP-15AC026TX.
After updating to build 1607, the sound on speakers(not headphones, they are good) are distorted or of low quality whenever I play videos on you tube or online video streaming sites.
To establish that this is due to a bug either in drivers and build 1607, I installed build 1511 and Windows 8.1 and surprisingly the sound on speakers are good.So nothing wrong with speakers.Hence problem lies with Windows 10 build 1607 and drivers only.
I tried different versions of drivers with no luck. (HP drivers,Realtek drivers and Windows update catalog drivers).
Any help appreciated.