Thanks a bunch for the tip on this app. It works fantastic!
I did get the app for free (v18.104.22.168) although you have to register on his forum to download the apk. Still, it was well worth doing so.
I'm not too worried about having the volume set too high as you need not run it at full volume all the time. I'll just set the volume rocker toggle to the middle setting and adjust as needed.
I followed the instructions on finding the maximum volume setting:
...open the Speaker Settings menu. Enable the “Audio Modifications” check box and then set the “Volume Level” to about +10. You should notice a boost in volume. You can then start raising the Volume Level until you notice either the volume getting quieter or the volume doesn’t change. You’ve now found your current device’s volume limit...
and found that 15 was the threshold. This is considerably louder than the stock setting.
The EQ presets seem pretty good and I like the fact that you can create and save your own EQ settings.
I haven't tried it with a headset yet but I'm sure the results will also be satisfying.
So thanks once again for suggesting this app.