Chad:
You may want to do a search for the topic of *lounges at AMS. In short it's a mess. There's a Singapore Silver Kris lounge there but it's never open on the days (Sunday) that I've flown out of AMS. SQ doesn't serve AMS on Sunday mornings so is locked up tight as a drum. I think you're out of luck as I was never able to find an alternative.
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Greetings from the land of 10,000+1 lakes.