macOS gives you one volume slider for the whole machine, which stops being adequate the first time a Slack notification is louder than the film. SoundSource puts a slider next to every running app and lets you send one of them somewhere else entirely — Music to the desk speakers, everything else to the headphones — without opening Audio MIDI Setup. The effects chain is the part people keep using: a ten-band EQ applied system-wide or to one app, and a volume boost past the macOS ceiling.
$49 is real money for a menu bar utility, and Rogue Amoeba's model is one payment per major version. Owners of SoundSource 4 or 5 pay $25 to reach 6, so budget for SoundSource 7 arriving eventually. In exchange the licence is per person, not per machine, so your laptop and your desktop are both covered.
Two things to know before buying. Per-app control needs Rogue Amoeba's audio capture component installed, which involves a permission grant and a restart — normal for this kind of tool, but not a two-click setup. And if what you actually want is an equalizer, eqMac covers that ground free or for $30 a year. SoundSource earns its price on routing, not on EQ.


