ati, acurus, aragon, emotiva, and outlaw immediately come to mind as affordable american made amp makers. the older, original five channel aragaon's are harder to come by and sell for more than $1200 used from what i recall.
The McIntosh amp would be one in a small group that would show the least amount of wear. If you find it has a problem there are many repair shops that specialize in Mc.
ATI makes mult-channel amp and they are assembled in California. Several of them are on Audiogon for sale. I have a 1505 and have been happy with it. It is a solid piece of equipment.
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