Waiting for the consummate rootsy-bluesy singer-songwriter Chris Smither to come on stage last weekend at Durham’s Blue Note Grill, we greeted our friend Michael the Sound Board Guy, who noted with a kind of respect-just-this-side-of-awe in his voice that the packed crowd was absolutely crawling with local musicians. Little wonder, given the “musician’s musician” label that Smither, now 76, has earned over a half-century of crafting songs that combine lyrical depth, humor, virtuoso guitar picking and a driving beat he keeps going with the slightly amplified foot-tapping that serves as his own rhythm section. “I can’t not do it,” he once told…