ROXY MUSIC IS among the handful of very best bands in the world. You didn't know that? You're not exactly alone, but the number of people who are aware of this band's capabilities seems to swell with each successive album release. Detroit knows it; they give the band Zeppelin-level airplay and a large enough following to fill the biggest hall in town. The same applies to Cleveland, proving that they're instant heroes wherever they're properly exposed, soft appears to be a matter of simply grinding out the yardage until they finally cross the goal line.