I'm using 22 ft long Harmonic Tech Truth Links unbalanced. Not a real expensive cable to be sure but they sound better in my system than some much more expensive cables i've tried. I have had no noticible increase in noise floor since i went from 1.5 m run to the 4 m. If your amp and preamp aren't truely balanced in their design, having balanced inputs isn't evidence of a balanced design, the balanced cables may not help.