The best alternatives to Cumulus are Soundnode, Soundbar, and Umbra app. If these 3 options don't work for you, we've listed a few more alternatives below.
What do you think of Cumulus?
Hurree— The smarter, simpler way to analyze your data
Umbra is a little menu bar app that lets you specify different desktop wallpapers for both light & dark appearances in macOS. Umbra also allows you to quickly toggle dark mode in a single click, rather than digging around in system preferences.
A SoundCloud app which integrates into your desktop. Never do you have to switch and find your browser tab again. With these native desktop integrations, you'll be listening to SoundCloud while being more productive.