Doubling a Set of Speaker Cables

It made day and night difference for me for my passive subwoofer.  The internal amp on my decade old PSB subsonic 6i subwoofer died.  I was using a radio shack PA250 amp to drive the sub.  Initially, I used a two feet long 18 gauge speaker wire to connect.  The sound was recessed.  Then, I used a three feet 14 gauge speaker wire.  The bass was immediately fully.  I was able to use some bass testing sound on youtube to measure the difference.  Then I picked up a long contractor grade extension cord from my neighbor's trash bin.  I cut a pair of three feet long, and striped three wire (black, green, white) on each end, and combine with a mono price Open Screw Type banana plugs.  Then the subwoofer made another day and night difference in extension and output.
Doubling speaker wire works well for any speaker can produce decent sound below 100Hz or all subwoofers.  For most stand mount speakers, the difference may not be heard by human ears. 

I have done a lot of experimenting with speaker cables in my system and in every case I have found running two sets of speaker wires improves sound noticeably. I have tried copper bar jumpers that come with speakers, copper wire jumpers, and silver wire jumpers and nothing sounds as good as running one set of wires to the high frequency terminals and one to the low frequency terminals. My theory (and it checks out with my listening tests) is that when one set of cables is used, whichever terminals it connects to will get extra current. Or at least it will have that apparent effect on sound. For a couple of years I bi-amped my speakers because of the noticeable improvement and sound quality. It took me a while to figure out that it was the second set of wires, not the second amplifier that was improving the sound. So now it’s one amp, two sets of wires for me. In my case I use Clear Day solid silver speaker wires, so a lot of detail is getting to my speakers. In my opinion when people say bi-wiring or for that matter high quality cables in general don’t make any difference, I politely say I think it’s a case of your ears or your equipment not being up to the task that is required to notice the difference

@milkdudd : exactly my findings and my experience over many years!

I also use one amp (two speaker taps, A and B, but can also bridge the single tap) using two speaker wire runs, one to HF and one to LF ports in my speakers. I will never go back to jumpers + single run speaker wire.

It's the total combined gauge that counts.

I use a double 8 foot run of Duelund 16g for a total of about 13ga and have been very happy with them. More extension and tonally denser/saturated within the images to my ear than the single run. Trying some other pricier cables now, but haven't found anything to displace them in my system yet. To be fair, I've tuned my system (yes, tuned) with them in place, so matching and/or improving on that becomes more of a challenge I imagine.

If that's the case after the next two, I'll likely give a single 12ga run a go (they make a nice tidy 2-in-1 run) for the fun of it and try to remember to report back.

FWIW, I used splitter and the Schroeder method with various sets of IC's and loved it for a while, but eventually the portrayal was overly saturated and off-putting with smeared tone and timbre sounding less crisp and accurate. So, maybe something doubled, something troubled - not being wed to any of it and remaining curious.....open ears, open mind. Open heart? "Free your ass and your mind will follow" (Funk Philosophy 101)