I meant to try something that isn't playing through your browser and ideally not streaming over the internet.
My typical method of troubleshooting is to change variables (or remove them) and see how that impacts the outcome. In your case, you're comparing -
1. an iPhone, using an App to stream via Wifi (or even via cellular) a song that is then wirelessly sent to a receiver that decodes it and plays it
2. a PC, using a browser to stream possibly via wifi or via wired connection a song that is then sent via a wired connection to a receiver that decodes and plays it.
So there are lots of variables here. So we start with the easy ones - we take the streaming and browser out of the mix and work with local media (I mean an MP3 or audio file or disk you aren't streaming). Another option would be to trying switching up the connections but that is likely harder.