Taperlark / Submix
Guides to per app volume, output routing and audio permissions on Mac. Learn how to adjust one app without changing another, send apps to different devices and choose a mixer for your setup.
Background Music failing to launch after a macOS update, sliders that do nothing, or sound gone quiet after uninstalling: which failures have fixes, which are the design, and what to run instead, with every claim attributed to the project's own README and issue tracker.
macOS has no per app volume slider, but the answer does not end there. The app's own controls, Safari's tab mute and the alert slider cover some cases, and a per app mixer covers the rest: one volume row per app, so you can lower or mute any of them alone.
Crackling, pops and dropouts after a Mac update are a documented chapter of macOS 26's launch. Here is the dated record from Apple's support communities and audio vendors, the workarounds that circulated, which ones make mechanical sense, and what a per app mixer honestly cannot fix.
Compare five SoundSource alternatives: free mixers, paid tools, and Submix with its full feature trial.
macOS has no built in per app volume mixer. Compare four approaches, then try Submix free during the trial or see what a license covers after it.
Submix gives every running app its own volume, mute, and live meter through a Core Audio process tap, with no driver and no admin password. Here is the mechanism behind the mixer, what it does not do yet, and who it will not fit.
Submix installs no audio driver, kernel extension, or system extension. It asks for one macOS permission, and this is what happens if giving your audio back does not go as planned.
Choose a different output for each app in Submix: music on speakers, another app on headphones. Follow the setup steps, then check permissions and device limits.