Does not work
Response from developer
Thanks for the honest feedback — both problems you hit were real, and both are fixed in the update that's on the way. The high-pitched noise came from Live Amplify. That feature feeds your microphone back to the output, so without headphones the mic picks up its own sound and squeals. That's on us — the app should never have let it start on the speaker in the first place. It now requires headphones and stops on its own the moment they're unplugged. On the volume: iOS doesn't allow any app to change the system volume or the audio of other apps, so the boost only applies to audio playing inside Volume Booster. If you turned the dial with nothing loaded, you'd have heard nothing at all — which sounds like exactly what happened. The new version opens with a demo you can start in one tap, with an on/off switch so you hear the difference straight away. If you're willing to give it another go after the update, I'd genuinely like to know whether it works for you. You can reach us directly at info@aswapps.com.