I can't taste my beer...or hear my cables

Let me start by saying I *do* believe cables "make a difference" in systems. I learned this early on in my exploration of this hobby when I moved from some crap Monster cable to Kimber 4PR (which I still use, kind of).

I recently had two experiences that bewilder me a little, however. I upgraded the cable between my pre and amp from HGA silver lace to Silver Audio Silver Bullet 6.0's. Nice upgrade. The HGA sounded thin compared to the Silver Bullets. Good deal there.

But then I bought the LAT Internationl SS-1000D speaker cable, thinking it would be an upgrade to my Kimber 4PR. Guess what? I can hear very little, if any, difference between the two cables.

Next: despite being a huge skeptic, I bought a couple of LAT International AC-2 power cables. These upgraded a stock power cable to my preamp and a "Basic Cables" power cable for the amp. I *may* hear a slight difference, but it certainly isn't much.

Other than hearing loss, what reasons are there for my inability to hear the difference in the cables? I have thought maybe the CDP (made by Denon) might be the reason, but that doesn't make sense, given the difference the Silver Audio cable made over the HGA.

Associated equipment:
Denon CDP
McCormack RLD-1 (soon to be platinumized!)
McCormack DNA-0.5 Rev. A
Infinity Overture 2 speakers (to be replaced by nOrh mini 9.0's in 2 weeks)

Thanks for your insight, folks!

HC