A note about starting the connection behind your stereo
If you were starting the flat cable behind your stereo, you’d probably run a short piece of regular speaker cable from your amp/receiver down to the baseboard, then have a similar connection to what I’m showing here as the beginning of your run. In my case, that wasn’t a good option since there is a gas fireplace next to the stereo. I ended up running a piece of speaker cable behind the fireplace (don’t worry, it isn’t hot) and used the slit in the drywall to get it onto the baseboard.