Go over to Audio Asylum, click on the FAQ page, then find Jon Risch's website. His DIY 89259 cross connect speaker cables have a design that lowers inductance, which is what you want for long speaker cable runs, while keeping relatively low capacitance at the same time. End result is it minimizes rolloff's over distance. It also is fairly inexpensive, being a DIY project.
Enjoy,
Bob
Enjoy,
Bob