I've always found Linn K20 one of the bizarrest cables I've ever come across. I've never liked it much because it proved to be so unreliable, and potentially so heavily influencing in the systems I've tried it in.
But in some systems it worked really, really well, as though it was magic, like an orchestra that had just found it's conductor.
But in some others it ruined the sound, hard, lean, lumpen bass, with confused timing. Just a mess like it was going through some sort of mixer, and with far greater impact than you'd think a cable could have.
What I've never worked out was why it was so hard to predict it's impact from system to system, or just what the mechanisms or interactions at play were.