“Hardcore Activity in Progress,” a one-night, 15-act concert Friday at the Knockdown Center in Maspeth, Queens, represented an idea. The idea was the sound of extremes — going for it, boundary-testing, hardness — across musical languages. So, for instance, there was the noise band Wolf Eyes, the cello improviser Okkyung Lee, the grindcore group Napalm Death, the rapper Gunplay, the post-minimal piano rhapsodist Lubomyr Melnyk, the free-jazz trio the Thing, and the electronic musician Tim Hecker, presented in overlapping sets, in three different parts of a 50,000-square-foot former door-frame factory.