$20,000 more spent on cables will give you... 4-5% higher performance. If you have the money then you should do this.
I think we live in a crazy world: some audiophiles are spending more money on cables than on their equipment. The biggest improvement in sound can only be achieved with the right equipment, system synergy and good quality AC power!! My buddy's FM Acoustics amplifier sounds already great with ordinary 14 gauge copper speaker cables. Using "top notch" and pricey speaker cables yields only a small improvement (somewhat higher resolution and a bit more extended treble).
Imho to spend on very expensive cables (let's say $10,000 for a pair of speaker cables) is the least beneficial step you would make with regard to sound. Of course there will be audiophiles who think I'm talking bullsh**.
Disclaimer: I'm not saying that expensive cables are useless, so don't get me wrong.
Chris