Hi - the internal impedance of your Lyra Kleos is 5.4ohms. Therefore the optimum would be the Low Z cable.
Thanks dover...Got the low Z one and upgraded the last remaining cables in all paths to SX and it's a really nice improvement. I'm able to turn things up much louder and I think getting a little more bass to boot, which ironically caused me to find a low frequency resonance on my tone arm at the higher volumes! Fortunately I moved the table away from the speaker at tad and can avoid it!
Thanks for everyone's help!