Fader

Pick any output device from the menu bar and your sound moves there: headphones, speakers, a display, AirPlay. The active one is marked, so you always know where audio is going. Drag a row and you set its priority; from then on Fader switches to a higher-ranked device when it connects, and falls back to the best one still present when the current default disappears. This ranking stays dormant until you reorder the list the first time, so nothing changes behind your back.

Bluetooth gets the same single click. Paired headphones that are currently disconnected still show up in the list; clicking one connects it and routes audio to it, and you disconnect from that same row. Wired devices you have not used in 30 days fold into a "Rarely used" group to keep the list short, and you can drag a row onto it to demote one yourself. System volume and mute stay in sync with your volume keys and Control Center.

Drag a device from the list onto the output section and both play together: one movie, two pairs of headphones, one plane. Each device in the group keeps its own volume slider, the ✕ removes it, and clicking any device in the list routes everything back to that single device. Try it in the popover above.

Fader builds this on the same multi-output device you could assemble by hand in Audio MIDI Setup, then removes it when you are done. Two things change while a group plays. The volume keys do nothing, because macOS gives a multi-output device no master volume — the per-device sliders replace them. And per-app faders pause, returning with their saved levels as soon as you are back on one output.

Every app that plays sound gets its own volume fader and a mute button. The levels persist across launches. Scroll the wheel or swipe the trackpad over any slider to adjust it without clicking.

An app left at 100% and unmuted is touched by nothing: no tap, no processing, bit-perfect native playback. A tap exists only while a fader sits below full volume or the app is muted.

Drag output devices onto an app and it plays through all of them at once, each with its own volume slider, so the desk speakers and your headphones can carry one app at different levels while everything else stays on your main output. A pinned device leaves the picker, owned by that app; its ✕ hands it back.

Unplug a pinned device and the app drops it, returning to your default once the last one is gone, then re-pins it the moment it is back. Try it in the popover above — drag a device down onto an app to pin it, set each device's level, or click a ✕ to drop one.

The microphone tab switches your default input and sets its input gain from a slider. On devices whose gain is fixed in hardware the slider disables itself, so the control never lies about what it can do. You also see which apps are using the microphone right now, which is enough to spot a forgotten recorder.

That indicator is the limit of what is possible per app. Core Audio exposes no per-app input gain, so Fader cannot offer one; this is an OS-level API boundary, not a feature waiting on the roadmap.

Most of Fader needs no permissions. Device switching, system volume, and the entire microphone tab work the moment you install. Per-app volume is the one exception: it uses Core Audio process taps, an API macOS 14.4 added and then gated behind the "System Audio Recording" permission. Fader asks for it the first time you move an app's fader.

The tapped audio is re-rendered to your output with the gain applied and never leaves the Mac. There are no kernel extensions, no virtual audio drivers, nothing to install in Settings. The name of that permission sounds broader than what Fader does with it, so I would rather explain it here than have it surprise you in a dialog.

Fader is a native Swift app for Apple silicon, macOS 15 and later, signed and notarized. Free under the MIT license, it is private in a way you can check: zero telemetry, zero analytics.