Subwoofer RCA Cable

It will depend on who you ask, but most people who believe in investing in quality cables including me will say yes. I say it like this because any cable thread is bound to go south on this forum. 

Sub cables typically have differences in both the conductor and/or dielectric (shielding) to prioritize the current delivery of lower frequencies and needed speed without worrying about the tone of the higher frequencies. Grounding quality is also highly paid attention to as many sub cable runs are longer and use RCA, whereas typical RCA interconnects should be 2M or less as to keep noise at a minimum.

As far as RCA sub cables go, I’ve only compared DH Labs sub cables, and not against cables that are meant for full frequencies. That said, the DH Labs Thunder cable, which is made of pure silver coated copper conductors, proprietary shielding and solid copper connectors were much higher performers than the DH Labs Sun Sonic cable which uses copper conductors. Stepping up to the Thunder resulted in much improved speed, definition and amount of kick. The Sub Sonic was much rounder and slower in comparison. 

@holmz You are correct in both points but it does not necessarily prove me wrong. Any lowering in impedance, say from an improved dielectric and quality of conductor typically results in a faster, more open sound. Yes there may be very little current, but whatever is there, you should want instantaneously.