Hi. The correct adapter for this model is an AC-D4HG. I could be wrong, but i don't think it was supplied with the player. It was an optional accessory.
If you want to get the most out of your D6C you overfeeding. Let me explain. You must use a 6 volt regulated power supply and at least 2 amper. Better yet, a lead acid battery 6 volt 4 amper. I use a 12 volt lead acid battery at 24 amper, I hooked a gearbox whose output voltage stabilized to 5 amper that I built for this purpose.