I haven't noticed any crackling in u64x, but I haven't played it in a while.
Prican, what do you mean about the buttons? They might need configuring once, but they stay saved, so you can have the buttons perfect. As for KI2 running too fast, that's how it seems on the 3D stages to me, I've got it for N64 and used to play it in the arcade, and I'm sure the 3D stages are too fast.