Audio works. new amp works fine, good volume level now connected correctly to. requires 12 volts though, so I added it to the split from the battery. that Now powers the Screen, the Megadrive and the Audio. seams happy with it though I'm now a bit less sure of the Battery life. Should be good BUT not sure what the full life is. will have to test.
Tested it and fully runs on the battery without problem. Need to connect up left audio channel however, but that is minor.
Still need to add Headphone socket. By the looks of how the circuit is, it would be best to add the socket between the Megadrive audio outs and the Amps audio in. this will, however, mean I cannot change the volume of the headphones unless I use a headphone with a built in control. most likely a minor thing though. I cannot see much of a way to add it otherwise. If I added it to the Right or left speakers, it would still allow that speaker to work, so that doesn't seam valid.. partly wishing I had picked a speaker that had a headphone jack in it but no real need and this is perfect.
Photos soon (Hopefully tonight) of my.. messy connections. Case Design for a prototype case underway at the moment. It'll be wood construction but I'm looking to replace it with Plastic at some point. Still need to relocate Cartridge Slot, Power button for Megadrive and Reset button for Megadrive.
EDIT: Nevermind about the headphone socket.. I'm an idiot and I remember where to put it now
EDIT 2: seams I won't get too much time for the photos till the weekend..