Performance Features Ergonomics Value PRICE $699 ($899 as reviewed) AT A GLANCE Plus Warm, tubey sound Headphone impedance switch New York born and bred Minus No DAC Too polite for some headphones THE VERDICT Woo Audio’s WA6 is a Class A headphone amp whose glowing tubes are voiced to warm up any headphones. The glow of vacuum tubes has fascinated me all my life. When I was a kid, my parents bought a Magnavox console TV with a built-in phonograph and AM/FM radio, the early-1960s equivalent of a home theater system with all the trimmings. It stood on 18-inch legs, and I loved to crawl under it, lying on my back to stare up into the orange glow of the tubes. My first few audio systems were solid state, but a cadre of die-hard audiophiliacs never really gave up on tubes. Now they’ve also wiggled back into my life and onto my desk, where the Woo Audio WA6 headphone amplifier sits, with three glowing obelisks keeping the retro audio flame alive.