Differential Sound is a feature in Viper4android - and i think many people do not know a use for it:
it can be used to correct the runtime in between your ears and your speakers in your car.
As the speaker in your car are at very different distances relative your ears (as a driver) the sound stage gets lost ...
People do buy high end stereo systems for their cars to get this feature ...
i was searching very long for this - until I found out that Viper4android does it (again - )
Try it out in your car - set the effect time to 2-5 ms and wonder about the little magic trick -
even though i use high end speakers and amp in my car - this little effect improved the sound by light years ...
(i got no connection with viper4android but am so happy with it, that i want to spread the word)