SACD and an audiophile question

I recently bought a DVD player that is also an SACD
player. Denon 1930CI. It has some nice features, including one called Direct digital. It basically turns off everything not needed, display etc.
I ordered a 2 channel single layer SACD. Boston's first album. I compared it to the normal CD you would buy at any walmart. I can hear a difference, but its very little difference.
First thing that came to mind is my system isn't really an "audiophile" system: The Denon mentioned above, Anthem TLP-1 Pre-amp, and Rotel RB960BX Dual mono 60w/ch amp, currently using Paradigm Studio 60's V3(stereophile class B rated)(Have a Linn Genki CD player, being repaired, and Magnepan 2.7's as well, not currently hooked up.)
While some would snub their nose at this system, it's still leaps and bounds better than anything you buy at BB or CC type stores. If I had $50k to spend on an audio system I would, but I'm married with children..enough said there...
I read sterophile and other mags about audio, and I noticed that they test equipment with really old CD/LP that I've never heard of. I always have wondered, Why do audiophiles test equipment with recordings from 1945 and 1964 etc. Recording techniques couldn't possibly be as good as what is possible today. Why would you not want the Best recording possible when doing a critical listening test. Seems to me you would be able to tell a piece of equipments limit if you had a recording that would expose those limits. Since the Boston CD was originally recorded in 1976, is it the recording a factor in only hearing minute differences or is my system so crappy that I "should" have a hard time telling the difference between a normal CD and a SACD?