The Creator app he runs on the Atari ST is a MIDI sequencer, not a DAW or sampler. The machine is probably not fast enough for realtime sampling. For sampling he is very well known for having used a pair of Akai S950s, each with 2.25MB of RAM. You can see them both on the rack behind him with the round yellow stickers. Just in case: this specific model also came out after most of the recording I mentioned.
Anyway, I was talking about 1986 and 1988... Rockefeller Skank was released in 1998. It's not exactly representative of a hip-hop setup from 12 years before. Either way, it is quite clear that he also samples from vinyl, like I said.
Anyway, I don't see how this is relevant to the topic. My point is that the sample was well known and was used in mainstream hip-hop from the beginning, it was never only an "underground secret distributed in disks"... that happened much later than the usage in hip-hop.
If there's any pre-1986 underground track using the Amen Break, or any documented use, it would be very interesting to know, because it would should be part of music history!