Just checked.
I confirm the RCA jacks on 600 and 1200 have a switch.
If only one plug is connected, the stereo audio out is mixed.
But, if you want to source this connector, take it from a dead motherboard (and I said really DEAD).
I suppose any Amiga, since A1000 have this very same connector.
In a second tough: why bother? Simply put conventional RCA jacks in it. I doubt anyone want to use mono in their Amiga, anyway. This feature is only useful with A520 or a mono TV set.
