[01010111]

Assuming the circuit worked the same as in the crowdsupply post and based on how much I had to attenuate the volume before the hiss became inaudible, I thought I'd need to reduce it between 20db and 30db. I tried some 50 ohm resistors. For my first time doing smd soldering, it was a success (even if it looks a little ugly). I installed the new resistors on top of the old resistors, because I don't have a hot air rework station. When I tested the results, I had to do a double-take. It was so close to how much I was attenuating the volume via dongle before, I had trouble believing it was that successful. It's now perfect.