Something recently was published in the medical literature showing that expensive placebo medicine seems to work better than cheap placebo medicine.
RL Waber, B Shiv, Z Carmon, & D Ariely Journal of the American Medical Association vol 299: pp1016-17; 2008
http://jama.ama-assn.org/cgi/content/full/299/9/101682 volunteers were recruited and paid $30 each to test a new pain killer drug. 41 volunteers were given pills that were said to cost $2.50 a pill, and the other 41 received the same pills, but were told they cost 10¢ a pill. All volunteers took identical placebo pills that had no pain killer at all in them.
Each participant received test electrical shocks at the wrist to identify his/her maximum tolerated pain level. After that, participants received the test shocks in 2.5 volt increments between 0 volts and their individual maximum tolerated voltage. They rated their perceived pain on a scale from "no pain at all" to "the worst pain imaginable". Stimulation at each voltage level was carried out twice for each participant before and after taking the pill. The change in reaction to the stimulation was assessed. The group that took the expensive placebo pill clearly thought it worked better than the group that took the cheap pill.
Something similar was found with wine tasting when the same wine was presented to tasters as $90 a bottle or as $10 a bottle
http://news.cnet.com/8301-13580_3-9849949-39.html.
Perhaps the makers of expensive speaker cable have known this for a long time, that expensive wires "sound better" than cheap wires. They seem to make a good living depending on this.
Usual DisclaimerI do not intend to insult anyone who does have expensive cables or prefers expensive wine. I only point this out because it is widely understood that differences in price have a genuine effect on people's perception of performance or quality. Maybe something similar is going on in audio.
I use 12 g zip cord on my SongTowers.