Visually neutral, XtremeMac's new Tango Studio ($80) is a budget-priced, black-colored iPod speaker system with a spring-loaded front dock, a fabric speaker grille, and an FM radio. The radio is tuned with top-mounted buttons and a nice blue LED tuning screen that's hidden behind the fabric speaker grille, and disappears when you're done switching stations; Tango Studio's only other audio sources are the docked iPod or an auxiliary audio device connected…