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.