i have this amp runnign 1 12'' l7. wen i have the gain like 1/2 way up i get almost no bass. i have to almost turn the gain all the way up to get any bass( iff i turn it all the way up and turn it back like 1/20th of a turn it lowers the bass a noticable amount and anything below that it really doesnt hit... should i just run the gain all the way up to get full potental?