I used CAT5 for all ELK connected speakers. (used the 8ohm surface mount types)
In fact, I used two pairs of the CAT5 cable to minimize resistance effects. Theoretically, cross-connecting the pairs reduces the electromagnetic field around the cable, which could be beneficial in your cable conduit. (ie. wht-brn+wht-or for spk+ and brn+or for spk-)
I doubt the Elk single gang speaker would disclose any further investment in speaker cable.
Regards!
Erwin.