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.

Your assumption is correct. Using balanced (xlr) creates 6db
more gain.

Hope this helps!

Check your amp manual to see how much difference in gain you have between the two conneciton methods (mine is 9dB). You can set both levels the same by using the balance control and a Test CD (like (XLO) that has a track recorded specifically to balance the ouput on both channels using a multi-meter.
Thanks guys, this helps alot.

This happens because you have a plus and minus version of the same signal, hence the voltage across the balanced signal is twice that of a single ended signal(RCA). The formula for converting this factor of 2 to dB is 20*log(2)
or 6dB.