❗ Visualization is currently disabled for Mac, cf. #154❗
The process is a bit involved and uses a an external tool and some sound configuration. First, we need to download and install the (free)
iShowU Audio Capture Device.
Next, open up the Audio MIDI Setup control panel in Applications > Utilities. We're going to create a multi-output MIDI device, so we can hear the desktop audio while also streaming it to the iShowU Capture Device.
Click the + in the bottom left, and choose "Create Multi-Output Device". Then, in the right-hand pane for this new device, make sure you tick "Built-in Output" and "iShow Audio Capture". Leave drift correction set to Built-in Output.
Close that, and head back over to System Preferences > Sound. You'll now have an output option for your new Multi-Output Device. Before you choose it, make sure you set your volume level how you want it: you can't adjust the volume of a multi-output device!
Lofi will automatically detect the "iShowU Capture Device" and visualizations should be working as intended.
Note: You'll need to create separate Multi-Ouput Devices for every output device you might use (e.g. a separate one for speakers and headphones). This is, unfortunately, a limitation of macOS.