Soundish

I was on a Discord call with music playing through Spotify and every time someone spoke it was either too quiet or my music was way too loud. macOS gives you one volume slider for everything. I just wanted a simple mixer — turn Discord up, keep Spotify low, mute Slack notifications entirely. Soundish does exactly that from the menu bar. You can also route different apps to different audio devices, so your music goes to your speakers while your calls go through your headset. One-time purchase, no subscription nonsense.