How do i chromecast from my stereo rig?

How do i chromecast from my stereo rig? I want to take the output from my d/a converter and cast it to a Chromecast device connected to powered speakers.

Essentially what I want to do is get rid of my speaker wires from my rig and instead cast to many different speaker locations, so I'm not limited to what I'm hard-wired to.

Usually you're going to cast TO the stereo equipment, using an input to the system from a Chromecast device. I'm curious about the use-case here...