This may sound stupid. But say I have track playing that has a BPM of 172, and I want to mix it in with a track that has a BPM of 175. So I'd drop the BPM of the other track I'm about to mix in to 172 and do the mix etc.......but when the original track fades out and so it's the new track that has an original BPM of 175 playing at 172, what do you do? Do you change it back to 175 or just leave it at 172? Surely if you don't change it back to it's original BPM it means the entire mix will have every track on the same BPM as the first track being played?