I'm surprised there isn't already a thread for this. I thought I might recommend a few apps I often use for audio stuff on my Android phone. I'm interested in seeing others' recommendations as well.\n\nNeutralizer\n\nNeutralizer is a 10-band global EQ app. What sets it apart from others is its method of dialing in the curve. The app plays test tones by octave and has the listener dial each band so that the tones play at the same volume. Neutralizer requires minimal permissions, and is offered as a freemium app. The free version allows storing only one profile. The ability to add additional profiles will cost you $5.\n\nIf you install it, just be sure to disable any app-specific EQ options within apps that offer it, and you might need to reboot your phone for the Neutralizer EQ to activate.\n\nMusicolet\n\nMusicolet is a free, ad-free music player app for locally stored MP3, FLAC, etc. It's lightweight, intuitive, has a flexible configuration (optional fade in \/ out, optional remember playback position on resume, etc), and requires minimal permissions. It's completely free, but the author does accept tips.\n\nSoundCloud\n\n... is my favorite streaming service for discovering new music. Free with ads every few songs, or $5 \/ month gets rid of the ads + allows downloading tracks for offline listening.\n\nHonorable mention: Audio Fx Widget\n\nBefore I found Neutralizer, Audio Fx Widget was the EQ app I used most. The widget is completely free, provides a nice interface for manipulating system EQ, and is very lean on its permission demands. However, it offers only 5 bands of equalization, 3 user presets, and the user preset labels can't be changed. Still, if Neutralizer isn't your cup of tea, you might prefer this one.