I have the side tumor Sega CD w/ a model 1 genesis. I hate it.
It is UGLY to the extreme. Did you get the little underpiece that sits on the left side to fill in that gap since the genesis 1 hangs off the edge like 3 inches?
You can use the typical cords for each, they work fine, and then run the audio out of the sega CD to a stereo and crank it.
I just know the genesis uses a different ac adaptor than the sega cd as far as specs on the adaptor..., Im not sure if it actually makes a difference, but if you get the ones that go to each youll be OK.