I am using 3.3.4 on an Amazon Fire Cube, Gen 2. At first I used VLC with the version from Amazon. The problem I will describe was not solved when I installed the APK via sideloading.
My file is UHD with DTS HD MA 5.1 sound. At one point the spaceship goes through a wormhole and there is very intense low subwoofer bass action. Using Kodi Matrix there is no problem getting this to play.
But on VLC for some reason the bass is reduced. I have verified the digital passthrough is set to on. To my knowledge, no EQ is being applied by the app. In fact, I am not sure the APK version has any kind of EQ.
Any thoughts? Thank you.