which XLR cables?

If both ends of your audio chain(ie: source to pre/pre to amp) are fully balanced/differential in construction: There are obvious gains to be had with regard to noise/RFI/EMI. That's IF your system requires long cables and/or resides in an environment with a lot of hostile interference(like a pro studio or live music venue). If your components are not actually fully balanced, but merely convert from balanced signal to unbalanced(or vice-versa) via an extra summing/dividing circuit: You're subjecting your signal to another processing step that will yield no benefits, and most likely will degrade your sound. (http://en.wikipedia.org/wiki/Balanced_audio) Mogami makes some decent cables, at reasonable prices, if you want to experiment. (http://www.musiciansfriend.com/navigation?q=mogami+cable&src=3WWRWXYB&ZYXSEM=0) The minimum quality I'd recommend for home audio(YES- There are very obvious and audible differences in balanced cables) would be the Kimber Hero though. (http://www.audioadvisor.com/prodinfo.asp?number=KKHEBAL) They can be found used here on AudioGon. I personally use Kimber's excellent KS-1130's between my BAT VK-D5 and TacT RCS 2.2(both fully balanced) solely for the 3db of signal gain the configuration offers. I don't bother with balanced between the TacT and my TransNova 9505 woofer amp(also fully balanced), because I would gain nothing in that application. Tried it- NO benefit.