Hi Redarrow, I have used bare 12ga on older Mac. Twist it tight and run 1/4 to 1/2 inch clockwise around the screw so when you tighten, it works together. Or Radio Shack has some gold pins for 12ga that you can crimp on and the pins will fit easily. If you want to go with custom cables there are 1/4 spades that can be ordered on them. That's what I did for the MC275 which has a barrier strip like you 7270. On the Maggies, the 4ohm is correct, + to 4 and - to C. Make sure both speakers are wired exactly the same. Good luck. BTW the 7270 is a great amp.
McIntosh 7270 speaker connections
Please help a Mc new guy. Have just purchased MC7270, w/o manual. Speaker terminals seem small compared to other amps I have owned (Bryston, Krell). Can only small-gauge wires be used on Mc amps? If not, how are larger wires used? Ques #2: I have Magneplaner 1.6, which are nominal 4 ohm. Connecting to 4 ohm terminals on Mc gives quite low gain--is this normal and usual? Any help greatly appreciated.