Running 50 ft. long speaker cables would be a mistreatment to driving amplifers, do unjustice to the driven speakers, and ultimately compromise the sound. If I'd had to go that route, I'd spend lots for $$ on near lossless long cables (impractical, still compromise the sound somewhat). Or, I'd use the $$ saved by not spending on 50 ft. quality speaker cables pair to purchase an alternative amp (a gainclone kit for example if you need more power than your Clari-T).
That said, if you still insist, I'd go buy some DH Labs solid silver cables.