I suspect many people can, but few of them are audiophiles. Whenever a non audiophile comes to my house and sees my six foot line arrays and tube monblocks they say something like "I couldn't hear the difference (between this and a mass market system). So I sit them down in the sweet spot, spend 30 seconds telling them what to listen for, and play something really sweet like a Nora Jones disk. After the first few bars it's clear to them that the system is better than anything they have heard before. When an audiophile comes to listen he is more likely than not to focus on those characteristics of the system he dislikes. Virgins are easier to please than whores.