"There is no physical reason why bi-wiring should improve a speaker's sound."
I've heard this sentiment repeated over the years by some very reputable sources. So why do many respected manufacturers continue to build speakers with two separate sets of input terminals explicitly for that purpose (that is, connecting a loudspeaker to an amp or receiver using two pairs of wire rather than the usual one)? Bi-wiring doesn't increase the power going to the speakers - it just doubles the number of cables connected to them. So what's the point?
According to many audiophiles and speaker companies, the answer's simple: it's the sound.
I decided to see (or rather hear) for myself if there was anything to this bi-wiring. Starting with a pair of four-way floor-standing towers I have at home, I disconnected the metal jumpers that joined the two sets of positive and negative terminals on the back of each speaker. Then I hooked up my two matching pairs of speaker wires between the speakers and my receiver. Once connected, I fired up the system to hear the results.
I was impressed.
Bass definition had clearly ratcheted up a couple of notches. Individual bass notes were much easier to distinguish, and they seemed to have taken on a fuller and rounder tone. High frequencies also improved greatly. The somewhat harsh brightness that I had always attributed to my speaker's metal dome tweeters disappeared - replaced by a smoothness and warmth I hadn't thought them capable of.
I performed the same experiment on a pair of high-quality two-way bookshelf speakers that I own. The results were similar although a bit more subtle.
The bottom line - even though I can't explain exactly why, bi-wiring worked surprisingly well in my system. If you have speakers that are compatible with a bi-wired connection, I would highly recommend that you give it a try. Happy listening.