Was never a big fan of spending money on cables when that money can be used for buying better gear or music. But after I replaced my previous speakers, my system was sounding a bit too dark for my liking. I was using QED interconnects and Audioquest speaker cables (the entry level ones). So the local Kimber Kable dealer offered me my current inter connects and speaker cables and asked me to try them on for free...I only had to pay for them if I had decided to keep them. To be honest, these cables acted like tuning forks. I am not sure if the sound is more detailed or anything of that sort cause I am too lazy for an A - B comparison, but the system has the right amount of brightness that I was looking for. So yeah, I decided to pay for the cables.
But that's it, not upgrading the cables anymore unless I break them!