Upgrading speaker cables...

In which case a new set would be beneficial?

I am in the process of finding a new set with the assistance of a very kind AG member. 

If anyone sees a set, pls feel free to lmk. 

belden 5000ue 12awg (true 12awg). PE insulation and OFC copper, twisted for low inductance.
Cheap and way overkill for a 6ft length - it would be pretty much like no cable at all.

I've fooled around with cables, and unlike most here, I actually dug into some theory and built my own. Nobody listening to $2000 speakers is hearing the plating on their cables terminations or jumpers. I doubt anybody listening to $20,000 is. The difference between an exotic cable an a piece of 12g is so miniscule that it's virtually impreceptible unless you're A/B comparing them on left/right channels. If the difference is more significant than that, then it's safe to say they're  highly reactive and coloring the sound. 
Maybe when I've got more money to burn I'll experiment more with cables. They're certainly not the tools I use to fine tune my sound. 

To those who say cables do not make difference in the system: its is because your system is not good enough. E.g. If you put an Odin cable in a system of $5k, you would not hear the difference but in a system of $50k, it would be much noticeable.