I use the XLO produced CD for "burn in", magnetic sweeps, and some set-up info., but for deciding on up-grading components, speakers, ICs, PCs, and spkr. cables, I use "real" music that I'm intimately familiar with. I've just never been able to get comfortable with "audiophile approved" music. IMO, you should use the music you really know and like to make up-grade decisions-- use good recordings though. Cheers. Craig