I think you're both right. :-)

I'll accept no duty on A/V equipment from the States.

I'll also accept duty charged on items made out of the States -- this is pretty much standard practice.

However, the actual charges would most likely apply to items being SHIPPED from overseas. Some guy in the back room of an A/V shop filling out customs documents ain't gonna look for the tiny "Made in Belgium" text on the bottom of the left side, so he'd just fill in USA or even leave it blank. Besides, they're going to put your order in another box.