Results from bi-wiring are dependent on a speakers sensitivity and how low they go.
My Salk HT2-TL speaker's sensitivity is 88dB with strong bass down to 34Hz. The Seas Excel W18 magnesium cone drives need current to maximize their performance. I discovered a single run of Kimber 4VS attenuated the bass. The 4VS has an aggregate wire size of 13 AWG, a double run has an aggregate wire size of 10 AWG, which is the sweet spot for the HT2-TLs. My test recording was "Temple Caves" from Mickey Hart's Planet Drum. A single run of Kimber has pretty good bass, a double run made the single pane glazed windows in my old house rattle.
If your speakers don't have strong output below 40 Hz or you use a sub with a high level connection (amp) then the wire gauge may not make any difference and 13 AWG to 15 AWG may work just fine.Our audio club recently auditioned the new Hapa Torsion 14 gauge UPOCC hand polished Copper and Torsion 15 gauge UPOCC Nano-polished Silver in two different systems. Both Eric and I found a single run of either cable attenuated the bass. Each of us came to this same conclusion separately while listening alone. Eric uses the 8 gauge speaker cable from GR Research.
https://www.audiocircle.com/index.php?topic=183932.msg1944092#msg1944092The Hapa speaker cables are a lot better sounding than the Kimber but I would need a double run and have no idea what that would cost. The difference in sound between the two cables was not subtle either.
Read my review about Hapa Torsion speaker cable and bi-wiring using both the Torsion Copper and Silver cable in a hybrid lash up.
https://www.audiocircle.com/index.php?topic=183932.msg1944092#msg1944092