If that's what he said, Robert Harley was wrong. One of the effects of bi-wiring is to change [slightly] the way the crossover behaves. You are essentially adding some resistance, capacitance, and inductance into the circuit that divides the signal between the drivers. The changes you make might be for better or for worse. If the designer of the speaker did a good job, you should use the same wiring system he did when he designed the crossover. If he used single wiring when he designed the crossover, changing from single wire to bi-wiring will only mess up his design. If he used bi-wiring, then you need to find out what wire he used, and in what lengths, so you can simulate the conditions under which he approved the design. Likewise for tri- or quad- wiring.
Benefit of Tri or Quad Wire compared to Bi wire
My speakers are four way and have fourteen bananas (7 red and 7 black) on the back. There are three sets of jumpers. I am about to purchase new speaker cable. Has anyone tried tri wire or quad wire? According to Robert Harley - you should at least bi wire when you have the terminals to do so. I am assuming there is diminishing return when you go to three or four cables. Please write your experience of tri or quad wiring, preferably compared to bi wire or single wire. Thanks, as always.