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A NAP150 would have a SNAIC5 (black). A grey 4-5 lead would most likely be a 4-5 Interconnect, either the early (slightly thinner) grey our later lavender/grey. There is though a rarity, which is a 5-4 SNAIC (for connecting a Dual rail PSU to a single rail pre-amp), but so uncommon that I don’t think I have ever come across one. There’s also a black 5-4 lead for the n-Vi, again, a rare one.