Axiom Home Page Forums General Discussion Technical Questions For biamping M60s, crossover need to be removed?

Not exactly. If you were biwiring but leaving the bridge on, you're using a big wire. That's what I do, just for the hell of it.

However, on the Marantz, you're actually using two electrically separate signal generators. So if you leave the strap on, you're routing signal from one amp into the other and vice versa. Then you get magic smoke.