Just to clarify: I understand that Poweramp doesn't know whether the decoder is applying any gain but the part I'm confused about is why Poweramp is unable to read RG tags. Is metadata being read by the android decoder and then passed to Poweramp instead of the tags (including RG tags) being read directly by Poweramp? Is this why Poweramp is unable to read or process RG tags but is able to display title, artist, etc?