I cut one, amp still works fine, what gives?

 

Power amps take a lot of current. Rather than run one heavy gauge wire they ran two thinner ones.

The current is maximum at high volume and during peaks in the music, so one wire will still work. One wire may get too hot from the high current draw. It also may 'starve' the amp of the current it needs to properly reproduce the sound peaks of the music into all the speakers.

 

Exactly. But I would add that it is most likely that the terminals themselves in the connector that will probably be overloaded with current first. The wires may not overheat, but the the current exceeds what the terminals are rated for they may overheat and begin to degrade. Then they will become more resistive, and the voltage delivered to the amplifier will drop, and so, likely, will performance.

 

Aha, better go reconnect that cable then. Power line filtering just got twice as expensive though.

 

Join them at the filter and split them on the way out?

A couple of inline fuses will still work if you ever have a problem.

OOPs, hold on, it's a Jaguar.