Using pipewire, and I’ve tried both the SB X4 USB DAC, and a SBX AE-5 PCIe card. Obviously being Creative products that’s the cause of my issues, but I have found it very very hard to find alternatives. Every recommended option just supports stereo, it seems.
KDE Plasma. I just like it. It seems to have options to do what I want, for the most part. There’s some things I wish it had, like a way to programmatically get the active window under Wayland, so StreamController could automatically change pages.