This is always an interesting topic.
Thru the decades I’ve been told here, and by wire sellers (go figure) 6ft. or 1.5M is the optimum length for most any cable. Or that has been my impression all along since reading these pages on various power and signal cables. Including digital links.
I gave more creedance to the far more objective accounts from members than from seller, although some times the input is congruent.
My next setup will not require lengthy spkr wires. I’m gonna have my 21ft SR active spkr wires cut down by SR to about half as long. Maybe less. Probably re-terminate them too.
Everyone so far that has borrowed these cables has brought them back saying they were very impressed. They’ve ben the most neutral conduit to the spkrs of any I’ve yet tried, regardless the amp or speakers connected to either end.
For all intents and purposes I can not believe two, three, or four feet added onto a two foot speaker cable will be as obvious as a 100lb pumpkin in a pumpkin patch. I can see how easier it would be to deal with however.
Add in the time needed to accurately account on these various lenths and additional distances, my thinking is its time poorly wasted. Unless…. We’re talking about an additional several thousand bucks for those two, three, ft or more. Or worse yet, per foot. Yikes.
Unless cost is an obstacle, having a few extra feet of cable often comes in quite handy as systems migrate and morph their ways along.
Naturally, as was said previously, this is gonna all hang on the spkr cable influence or lack thereof.
I’d also say if I wer a spkr cable maker I’d try to make what ever level of cable sound the same as it does in shorter lengths or perhaps longer, within reason given electronic constraints.
Audible per foot? Unlikely. Cost per foot? Could be serious.
Very good luck going forward.