Ummm REMOTE IN connection on stereo receiver / IR Extender

Ok, I'm feeling like a dunce. I've got a 3.5 mm REMOTE IN jack on the back of my peachtree amplifier, so I thought I could buy one of the low cost IR extender cords and plug it in, to get better remote control access. (The amplifier sits in a closed cabinet otherwise and blocks the IR remote).  But apparently not, or at least the cable I bought doesn't have the required frequency.  I'm being told two separate things that don't make sense. One person said I needed a powered IR receiver that then has an emitter for the IR sensor on the amp (if so ... why the hell is there a REMOTE IN), the other said I must just have the wrong cable and need to know frequency matched information.

This thing has got to be just a photodiode. Is it really this convoluted?