Default [Q] CM11 0702 nightly Audio

Hi Guys!

I was using CM11 0613 nightly for a few days, everything was well.
updated yesterday to CM11 0702 and audio was very weak on Spotify and other players.

I searched and back read on the thread and I flashed a zip that they provided on the cm11 thread and audio is still weak.
I restored to my back up of the CM11 0613 and audio was loud again.
I'm back on the latest nightly and audio is still very weak.
next solution that I found on that thread is to use viper4android and change some audio drivers.

is it safe? how can I back up audio drivers before replacing them? will restoring my nandroid backup restore the audio drivers as well?

Thanks in advance!