Has anyone had any listening experience with the Monster Cable Z4 or Z3 speaker cables. A friend of mine had another name brand of cable and tried the Z3 and said the left/right imaging was much better and the highs were more resolved. I currently use XLO ultra cable and do like them but I wonder if the Z3 or Z4 might be better? Apparently Circuit City sells the Z3 for $168/pair for 10 feet and the Z4 for $224/pair. Any opinions?? Thanks!