Sound

Set each app's volume and output, change the Mac's volume and output from the bar or a hotkey, and mute every microphone at once.

Volume Mixer

Type volume mixer (or mixer, app volume) and press ↵ on Volume Mixer. You can also give it a hotkey on Settings → Hotkeys.

Turning one app down with ←, then sending it to other speakers from ⌘K → Output.

The mixer lists:

Devices: your output and microphone with their levels, and where alerts and sound effects play.
Apps: every app holding audio, each with its own slider from 0 to 200 % and the output it plays on.
Options: press ↵ on it to show the settings described below.

Key	What it does
`←` / `→`	Turns the selected output, microphone or app down or up, 5 % at a time.
`↵`	Mutes or unmutes the output or the app. On the microphone: Mute Microphones. On alerts: picks where alerts play.
Type	Filters the rows by name.
`⌘K`	Everything else for the selected row.

An app's ⌘K

Output › sends that app alone to another device, or back to Default.
Reset to 100% (⌘R), Turn Up, Turn Down, Mute.
Pin to Top (⇧⌘P) and Move Up / Move Down (⌥⌘↑ / ↓) set the order.
Hide from Mixer takes it off the list. Show it again from Options → Apps in the Mixer.

Some call apps also offer Turn Off Volume Control (for Sharing Audio), which leaves their sound to the app itself; Allow Volume Control brings the slider back.

On the output, ⌘K → Output › changes the Mac's output. On the microphone, Microphone › picks the input.

Permission. The first time you change an app's volume or output, macOS asks for System Audio Recording. The app's sound passes through Saiki so its level can change; nothing is recorded. Saiki remembers each app's level and output.

Options

Hide apps that aren't playing, Show Finder and Lower the volume when headphones disconnect: ↵ turns each on or off.
Switch Sound Output: each output, "In the cycle" or "Skipped". ↵ includes or skips it.
Output Priority and Microphone Priority: the switch, then your devices in order. ⌥⌘↑ / ↓ moves one.
Apps in the Mixer: each app, Listed or Hidden. ↵ shows or hides it.

Volume commands

These act right away and a small message shows the new level. Each can have its own hotkey on Settings → Hotkeys, which runs it without opening the bar.

Type	Command
`volume up`	Turn Volume Up, by 5 %
`volume down`	Turn Volume Down, by 5 %
`mute`	Toggle Mute
`set volume`	Set Volume to 0%, 25%, 50%, 75% or 100%
`volume 40`	Set Volume to 40% (any level 0–100; `vol 40%` works too)

Some outputs don't let the Mac change their volume. Saiki says so instead.

Switch Sound Output

Switch Sound Output moves the Mac to the next output in your cycle and says which one, for example "Output: AirPods Pro". The cycle is every output until you skip some in the mixer's Options. Give it a hotkey on Settings → Sound, in the Switch Sound Output card, which also lists the outputs in your cycle.

Device priority

With Switch to the highest-priority output on, the first connected output in your order becomes the Mac's output, so plugging in your headphones or turning on a speaker switches to it if it ranks higher. Switch to the highest-priority microphone does the same for input. Both are off to start with. Set the order in the mixer's Options; a new device joins at the top when macOS picks it.

Mic Mute

Toggle Microphone Mute turns off every microphone the Mac has, not just the default, so an app using its own headset is muted too. Each microphone uses its own mute when it has one; otherwise its level goes to zero and comes back when you unmute. A microphone plugged in while muted is muted as it arrives, and the mute lasts through a restart of Saiki.

While muted, a red crossed-out mic shows in the menu bar. Click it to unmute. Give Mic Mute a hotkey on Settings → Sound, in the Mic Mute card.

Headphone guard

Turn on Lower the volume when headphones disconnect, and when your headphones disconnect the speakers drop to the level set in Speakers after headphones disconnect: Silent (muted), or 10 %, 25 % (the default), 40 %, 50 %, 75 % or 100 %. When the headphones come back, the speakers get their old level back, unless you changed it in the meantime. It's off to start with.

Settings

Everything is on Settings → Sound:

Card	Rows
Mixer	Hide apps that aren't playing (off), Show Finder (on: Finder's own sounds get a row), Hidden apps.
Headphones	Lower the volume when headphones disconnect, Speakers after headphones disconnect.
Switch Sound Output	Its hotkey, Outputs in the cycle.
Device Priority	Both priority switches, Output order, Microphone order.
Mic Mute	Its hotkey, Show in the menu bar while muted (on).
Permission	Whether System Audio Recording is allowed.

The switch at the top turns all of it off. Nothing then watches your audio devices, and a muted microphone gets its level back.