[davida]

I went for it an connected up an iPod to the "Gramo" connector in the chassis.
I got an old pair of earbuds and cut the left one off, stripped the ends of the wire and poked them through the top of the plug and folded them around the ends of the pins, then pushed the plug back into the socket.

It seems to mix the two inputs and I have to detune from a radio station to get just the iPod.
The volume has to be turned way up on the Philco and it is a bit distorted because the volume has to be up quite high on the iPod as well.
I expect this is because of and impedance mismatch somewhere. I have no idea how to correct this.