@gavin1977
I have two Synergistic Research cables (Kaleidoscope and Looking Glass) and an older XLO Ultra cable. I do seem to lose some sq with those. I also have a Morrow Audio MA-5. No real complaints about it. I have Core Power Technology Diamond cables. They aren't bad.
I think it's all about system matching. I thought I had wasted my money on the Harmonic Technology cable. It's been sitting in it's box for a while.
The DH Labs Air Matrix is very good, too. At least it is in my system.
I haven't tried any super expensive interconnects. My speaker cables were $1500, but I haven't spent nearly that much on ICs. I like how my system sounds now, so I probably won't try more cables.