Different lengths of interconnects ??????

It will work perfectly if you place the speaker using the shorter IC 18" further out and toe it in three degrees more. ;) Seriously, buy equal length IC's; if you ever rearrange your gear and are short on one IC, you'll kick yourself. Think long term, which for gearheads is six months.

There does not need to be an actual audible difference to be bothersome. If you're asking about it, it's quite possible that it will play on your mind. If you weren't worried, you would likely have purchased them already. As it is, you may obsess over perceived differences. If so, then it's not that much of a bargain when you're ruminating over it all the time. Only you know if it would bother you or not.

FYI, in my office, one run of speaker cable is approx. 6-7' longer than the other. I am absolutely unable to perceive any effects from it. But, I found I had to put the balance control at 9 O'clock. hahahahaha

Kurk_tank, you are confusing the movement of electrons in the wire with the signal (electromagnetic field) traveling down the wire. They are not the same thing. It is the signal that we are concerned about. The movement of electrons is a side effect caused by the field that is following the wire.

Electromagnetic waves travel fastest in a vacuum, slower in any other medium. Since light is an electromagenetic wave this speed is usually called the speed of light. In a wire it depends on how the wire is constructed and is expressed as the velocity facor.

http://en.wikipedia.org/wiki/Velocity_of_propagation

Keep the same lengths