I think your friend probably reads way too many audio magazines, and was trying to impress you with some foolishness he just read. Why not try this instead, invite your neighbor or the kid next door over to listen to the rig using their favorite CD's or LP's, all the while switching cables back and forth to elicit a comment. I think you'll receive a much fairer and objective answer to your question, IMHO.
How high end must your system be...
...for you to be able to notice the differences different cables will make. I've always said that I have ears of tin until a friend of mine came to my house and said that my system was just not high end enough to be able to hear the differences different cable will make. My system isn't the newest but it wasn't that cheap. My system is valued at several thousand dollars and I don't think I have anything in my system that you can find at just any audio store.
So, how high?
So, how high?