Speaker cables generally cost more so the 50/50 rule is not valid. If you spend $1500 on speaker cables then you will have $1000 left for i/c's which may be a couple of 1m pairs.
Your opinion on cable spending
I will be looking to replace my current interconnects & speaker cable within the next couple of months. I can budget up to $2500 for i/c's & speaker cable, my question is do I spend more on i/c's? Or spend more on speaker wire or budget around 50% for both? Your opinion & why would be appreciated.