A contribtion to
Down In It (registering still seems disabled?):
Producer Keith LeBlanc mentioned in
a printed interview that "Down In It" was the song he got to "really put my signature on". His revisions - the Shred, Singe, and Skin mixes - draw heavily from the tracks "Mechanical Movements" and "Einstein" from his album
Stranger Than Fiction, released earlier the same year (1989). The fast-paced synth prominent at the beginning of Skin is from "Mechanical Movements", and the main drum pattern is from "Einstein". Additionally, the crowd chant samples during each chorus have appeared in other works involved with Keith's band Tackhead, such as Gary Clail & Tackhead - Reality and The Barmy Army - Stadium Rock.
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Head Like a Hole (Opal):
It features a sample in the choruses that also forms the main rhythm of Mark Stewart - The Wrong Name and the Wrong Number. Adrian Sherwood was involved in the production of the Stewart song, and he and Keith LeBlanc were both members of Mark Stewart and the Maffia at the time they produced Pretty Hate Machine, though whether they had direct involvement with the Opal mix is unknown. LeBlanc and Sherwood aren't credited on any of the Head Like a Hole versions except Keith's mixing of Slate.