Security at AMS for USA flights depends on whether you have Sky Priority or not. If you have Sky Priority, you check in at a dedicated group of counters (as I recall, it was area 11-12), and, after you check in, you don't go back out into the common areas to head for the security entrance; instead, you proceed to a dedicated security line, where you put your boarding pass on a scanner on the gate, and it decides whether to let you in. You then go through the security scanners, and then you go through passport control (which was semi-automated in that you scanned your passport, but then you had to be authorized to leave the area by a member of the Marechausee (Dutch customs police). After that, you were in the non-Schengen area. If you have lounge access, your lounge is called "Crown Lounge 52", which is near the entrance to the F concourse. This is one of my favorite lounges in the Delta/AF/KLM system.

The non-Sky Priority passengers had their own line and group of check-in counters to use. I think they ended up coming out of the process in about the same location as I did when I was there most recently in May.