I may be wrong, but I always thought the standard argument supporting equal cable length had less to do with signal delay as it did with inductance, reactance, and capacitance (those terms could be wrong, it's been a few years since I stumbled through E&M). I know that for direct current a solid conductor with uniform cross section has resistance proportional to length (and inverself proportional to cross section area). As such a 60% increase in length seems like it would have fairly measurable effects on the current. I know that this is a not quite correct, complete oversimplification of the argument, but I think it's along those lines. Anyway, the final measure of course is what you can hear. Perhaps a good experiment would involve getting a ridiculously different lengths of zip wire and seeing if that makes a difference.
