Whats wrong with short cables?

Hello Fellow Audionuts!!!!

Just curious....

Why should speaker cables be 8 feet and over? I hear that sometimes shorter cables can cause blown tweets and such during extended guitar solo's and stuff like that.

I always kinda assumed the shorter the run the better.

Im researching into building my own Pre, SS Amps, Speakers, and cables. I was planning on running a stereo amp pair for each speaker and bi-amping them. The amplifiers will be on thier own stands between the pre/cdp/tuner and the speaker. That means i will have a speaker cable run of probably less than 4 feet.

Would it be better to tailor the legnth of the cable to the distance needed? or would it be better to use a cable over 8 feet in legnth and just have it coiled behind the speaker?