More gain using XLR cables?????

Hey folks. I auditioned a pair of Harmonic Tech Pro Silkway II RCA interconnects last night against my taralabs RSC ref XLR cables. I wanted to do a side by side comparison so I hooked up both RCA and XLR cables from my CD player to my pre-amp; I am not sure if this lessen any sound quality or not but I did it anyway. The initial difference that I noticed is that RCA cables required more amp/current (I mean I had to crank up the volume) to be able to listen at the same level as the XLR cables. Can some one comment on why this happens? After about ten minutes into the CD, I can tell that HT interconnects opens up my system more than the Taralabs. Thanks in advance for any comments and opinions.

Nick