how much should you spend on cable?

FWIW, I started by spending as little as possible on a recent system build ($2150 1st audiophile system for a friend) - cables came out to 15% of the cost, and performance improved markedly with every step. Most of my systems have wound up with 10-20% in speaker/IC cables.

I think I'd be scratching my head at > 25%, wondering what went wrong.

Anyone who tells you there isn't a forumla is correct, the numbers I gave are just from my personal experience.

I don't know that you can put a price on cables. If you find cables that provide you with good system synergy and they cost .01% of the rest of your system, does it really matter? I don't think so. On the other hand, if I had a 5000 system, I wouldn't be looking at Kimber Select Black Pearls either.

That's the difference between audiophiles and other people who also have good equipment; we try to extract maximum performance from what we already have.Cables are components and should be treated as such.Generally speaking and operating with m.s.r.prices, I would say 50% the price of CD-player and pre-amp.for 1.0M pair interconnects and 50% the price of speakers for 8'pair of speaker cables is within reason.Personally,I followed this rule for interconnects, and my speaker cables are more expensive than speakers though I bought them for less than third the m.s.r.p., so in fact they are a little less expensive than my speakers.Power cords usually make less profound effect: 10-20% the cost of the component should be enough.

Inna:

"50% the price of speakers for 8'pair of speaker cables is within reason"

I guess I have to disagree. If cables are components they are passive components. A speaker has to transform electrical energy to magnetic energy to mechancial energy to acoustical energy. A cable only needs to transfer the signal. A spending ratio of 2/1, speaker to speaker cable, is pretty crazy if you ask me.

I remain,

Reviving this thread in light of recent discussions here on cabling.  I am currently running two systems.  On my main system, investment in cables is about 20% based on retail prices.  On my secondary system my investment is closer to 40%.  In both cases, I think the cables are appropriate and have increased my enjoyment considerably.  Interested in your thoughts.