best speaker wire for extra long runs


I have a 45 foot disctance between system and speakers. Currently I use whatever the thickest gauge Monster speaker wire is - I forget the specs. Is there an upgrade option that will not break the bank that would be a really significant upgrade from the Monster for such a long distance? The only option I have seen is from Cardas, but I do not have a sense of whether that would provide a significant step up in sound quality from the Monster. Speakers are Sonus Faber Grand Piano.
gipp
My run was not nearly as long (19'), and it was not for my primary listening speakers; but I have had good luck with Analysis Plus Blue Oval. I'm using the cables with a Creek integrated and Audio Physic Speakers.
I'd like to suggest Morrow SP1 speaker cable. I just changed to a 30 foot pair of these for my rear channels and they are wonderful. Huge soundstage, transparent and very dynamic.
According to this, it's all about wire gauge, distance, and speaker impedance.

If you choose to believe it, then Monoprice has some of the best prices for speaker wire. If you need 10 gauge, I recommend Blue Jeans Cable.