IEC to a 2 prong-wire amp

I've also done this. The only difference from what Albert said is I bought a nibbler tool from Radio Shack (I think they're about $10). It "nibbles" out chunks of sheet metal - one at a time that are approx 1/16"x 1/4". Since I centered the IEC recepticle over where the old cord was, I didn't have to drill, simply began nibbling from the original hole out. I finished with a hand file (the nibbler leave ragged edges and went to go real slow for the final fit so I didn't cut too much out.

You'll want to be careful that metal cuttings don't get lodged on circuit boards and creaqting a short.

I also left off the ground wire . . . same rationale as Albert's.

if you're referring to polarity, it's likely that the IEC will indicate "N" for nuetral; "L" for live, "E" for "earth" , or something similar. I'm looking at one now and that's how it's marked. If it's not, the Live pin is on the left side if you're looking into the receptical where the cord plugs in, with the ground pin on the top.