Just got a ChromeBit for the home office, so I can browse to Facebook and other sites blocked by my work laptop, and not have to deal with its VPN, which doesn't let me cast to my home network.
Found out quickly that casting to a CCA from a browser tab sounds like crap from just about any source. They must be using a VERY highly compressed, very low bitrate stream, it's choppy and full of artifacts. Not good.
Found this Chrome extension called "Add To Sonos Queue". Enabled it, set the IP address to my left Sonos Play:1 in the Office. Navigated to SoundCloud, picked an album, hit the button, and it added the current album, all songs, to the Office Play:1s' playlist. The "Play" button in the browser wouldn't work, but I just asked the Office Echo Dot to "Play", and it started. Full fidelity, as the browser and ChromeBit are out of the picture, just Sonos directly from SoundCloud.