There have been several times where my system made a big leap forward. Holding speakers constant, new preamp/amp, superb power conditioner, dedicated AC line. Nevertheless, the most cost effective - though not cheap by any means - was installing better AC cables (Darwin Truth Black and Red to be specific). Everything, but especially presence, improved dramatically, The improvement was not subtle at all - I felt like I had upgraded a major component. I agree with Miller Carbon that it is futile to put a percentage on how much to spend on cables, but they should be treated like a component, not an afterthought. I have come to believe that focusing on power supply and transmission has a huge payoff. Also, it is not necessary to spend a ton of money to get good quality. Signal produces really fine cables at a more than reasonable cost. Cheers!
