Rogue Amoeba | SoundSource: A Superior Sound Controlのページにて、アプリ毎にボリュームやイコライザーの設定をすることができる、「SoundSource 5.3.9」が公開されていました。（有料）

• SoundSource now includes AirPods 3-specific art.
• When the SoundSource window is pinned, clicking the menu bar icon will now reveal it, instead of calling it back to the menu bar.
• SoundSource's volume sliders have been improved, dimming the thumb when muted, and unmuting when the knob is moved.
• An issue where Firefox audio could appear twice in SoundSource, under a “plugin-container” process, has been rectified.
• As a result of changes to MacOS, the Shortcuts app erroneously showed non-functional Shortcuts for SoundSource. This has been corrected, and we hope to add proper Shortcuts support to SoundSource in the future.
• In future updates (5.3.9+), SoundSource's update progress bar will no longer float above all windows while your download is in progress.