At this high-end-yet-casual men’s boutique, you’ll find designer suits as well as casual cashmere sweaters. But when owner Brent Collier (who also runs the larger Collier showroom downtown) isn’t traveling to Italy in search of the perfect hand-stitched Brioni jacket or luxurious silk and cotton dress shirts by Ateseta, he’s searching for a little rock ’n’ roll on the side. As evidence: Collier also sells Sugarcane and Kato, two cutting-edge Japanese denim lines that are extremely hard to find elsewhere in the United States.