It would be nice to have values by the side of each EQ bar, or at least let us know the default +-db limit so we can divide by the number of steps.
I was trying to find this out myself, and after doing some searches it seems this question has been around for a while.
So I decided to do an experiment and find out the EQ steps for myself. Executive summary: each step in the EQ (by tapping above or below the slider) is 1.5dB
Poweramp full version v3-build823
All audio processing done in Adobe Audition
I created a 24/48 flac file containing a -20dB pure 1kHz tone in Audition then played in in Poweramp on