What tool can I use to measure the volume of .mp3 on my S6 + make the volume all the same? I have powerAmp paid and I have mp3's from different sources. How do I measure the decibel levels of each clip + adjust it to make it the same? I used to use Mp3gain on the desktop. Anything like that for Android on and S6?
PowerAmp can read ReplayGain values written to the mp3 files, but does not do any analysis itself.  The best option would be to apply ReplayGain tags using something like foobar2000 on your desktop, and then copy those files over to your S6.