I've tried connecting the headphones directly into the soundcard as well as the control box, firmly, and either way I only hear out of one side. I've also messed around with the software to confirm both sides were balanced as well as making sure the headphoes work on a different device. Still nothing.
After more googling I discover another connector, TRRS
. Turns out the other ring is used for mics, which makes sense if this control box thing for gamers caters to headphones/mics. Still, why would using a common TRS headphone plug inserted into the control box or directly into the soundcard's headphone input only produce sound from one side? I plugged my earbuds w/mic, which has what appears to be a TRRS plug, into the control box and can hear from both buds but one side was louder and crackled.
So unless anyone can confirm/deny my new findings then I will probably purchase this adapter
to connect to my headphones. I'll report back if I do.