Cool Sound App for Mac

Compatible – All features are fully supported on macOS 10.11 – 10.13.x, including macOS High Sierra.
Each EQ can be 10 or 31 bands. EQ – Use a system-wide EQ or set a different EQ on each app.
Cool Sound App for Mac
Full Hotkey Control – Set up hotkeys to control volume, mute and EQ for the foreground app. There is even a hotkey to mute all background apps.
Control the audio of each of your apps independently with per-app volume, EQ, and audio routing. Sound Control is a unique application that adds advanced audio controls to your Mac.
Audio Routing * – Reroute app audio to any audio output device.
Send iTunes to an external USB device while the rest of your apps use your MacBook’s internal speakers.
Static Z Software thinks so, too.  Here is what they say:
Sound Control by Static Z Software Shouldn’t you be able to adjust the volume level for each of your apps? Have you ever been surfing the net listening to music when you unknowingly click a link to an auto-start video only to have your eardrums shattered by the blaring video? But last week I came across Sound Control by Static Z Software. Besides, only a handful actually work. There have been several half-assed attempts at making plugins/extensions, but very few for Safari. Not only does it control the volume of your browser, it also lets you manage all your other applications in one convenient place. Of course you have!
Touch Bar Support – New in Sound Control 2.2 is the option to use the Touch Bar on your MacBook Pro to control app volume.
Volume – Add keyboard volume controls, to DisplayPort monitors, HDMI TV & Receivers, and other devices missing them.
Per-App Volume Controls – Control the volume of your apps independently.
So check them out if you are interested in having more control over the audio on your Mac. We are working on a solution. Sound Control does not currently support the internal speakers of the 2018 MacBook Pro’s or 2017 iMac Pro. USB and bluetooth devices are supported.
*Audio Routing not yet supported on macOS 10.14 (Mojave)