What you need is <= 12 gauge wire but even more importantly, very FINE stranded wire with MANY strands. Higher frequencies tend to be affected by the skin effect and over such long lengths, the resistance will add up. The more strands there are, the better it will be.
I'd like to upgrade my speaker wire
I am fairly new here and still learning. I have a Yamaha R803 receiver and Vandersteen model 1s. I'm happy with them for now but I'd like to upgrade my speaker wire. I presently have 14 gauge wire I bought years ago at Best Buy. I need 40 feet. I've read great reviews about Back Cat but I think 40 feet may be a little pricey for me. I'd greatly appreciate any advice on a good quality wire at a reasonable cost. Maybe under $500? BTW, I bought Jim Smith's book as recommended here, great advice, thanks. Doug