Michael uses a Chromebook in the garage for working out. But the video is rather janky. So he added a Chromecast and a video monitor. The Video is improved, but he doesn't want separate audio output. Leo says the HDMI carries both audio and video, but you can split it into a stereo. Leo adds though, that it can be tricky because you'd need a powered speaker to do it. Michael is currently using a headphone jack connected to computer speakers. Not really optimal.
Leo says that the JTech Digital interface is pretty capable because it has an auto-return channel capability, and can connect the Chromecast to it. But it's not an amp, so you'd need to add that as well. Pretty capable for under $40.