Right, I use a TT-BA08 to plug my cheap cable headphones in (since most new Smarthones ditched the 3.5mm), which connects to another one which is only a sender (and has no volume controls). That sender receives a line-out of a little analog mixer into which a PC and other devices plug in.

This is quite nice, because it allows me to stand up and walk around while the PC continues its audio playback.