This is a simple headphone or loudspeaker matching unit that I made from an old tape recorder PSU that I picked up on a car boot sale for 50P. It was a 6Volt output type. I opened it and removed the PCB. I also removed the three mains pins, live, neutral and earth. The old output wires were disconnected from the low impedance side of the transformer and soldered to the old mains input side. I fitted the wires with a 1/4 inch jack plug. A hole was then drilled in the case to take a 3.5mm stereo jack socket. This was connected in mono configuration to the old 6V winding. A standard set of low impedance stereo headphones can now be plugged into the unit and the 1/4 inch jack plug plugged into the equipment. I find this very useful when making small receivers when I don't want to have a matching transformer in the equipment itself!
These old recorder PSUs are a very good source of cheapo transformers for all sorts of uses! The PCB has often failed, but the transformers themselves are generally OK