Many people use 18ga or 16ga primary wire to make twisted pair RCA cables and I have too in the past. The wide variety of colors can make for some nice color matching to a system.

Usually primary wire is pretty basic quality though and I don't care for how the twist can separate and get random around corners and such. For mine I used 18ga EFX speaker wire. It's OFC, I like the blue and silver, and there is no chance the conductors will separate since they are bonded together.

For ends I used Stinger Bullet series. They're all metal, have teflon isolation, and are easily accessible. Plus I can buy an 18" or 3ft cable, unsolder the ends, and throw away the cable for less money than buying two pair of most other metal ends

 

I`ve tested some high end RCA`s including the Cardas Golden reference beauties as well as several other similarly priced ones and could not hear a difference between any of them and some relatively inexpensive cables.
build quality, durability and shielding should be the primary focus of these wires....

 

Yeah, what he said.......

The only thing I've ever insisted on is twisted pair wires for noise rejection....I have paid anywhere from $30 to $100 a pair for them and never heard a difference between them.....having said that I have also never had problem with noise in my RCAs.....so there ya go......