How high end must your system be...

Rather than tilt at windmills, it may be better to list the items that comprise your system and go from there.

In general, well designed power supplies and an overall low system noise floor will reveal differences in wire.

My first system that lasted cost about 4k(1990 dollars, some were demos), a Conrad-Johnson MV-52 amp, Pv 11 preamp, B&W matrix 804 speakers and a Sonograph SG3 turntable, arm and cart all included plus cables. On it, differences in cables was easily heard. Was this high end? It made music for me and improvements have followed. As more than one person has said on this forum, if you can't hear the difference it may not be there. So, maybe you have just lucked out and have a room and system that match well enough e but one that just works. What more can one ask?

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.