If you wanted to listen to the digital AM/FM broadcasts beaming out across the US from nearly 600 stations, you were stuck until recently: car receivers existed and a $1,900 Yamaha component receiver. The three companies working to push out tabletop radios with built-in speakers had many delays. Boston Acoustics announced yesterday that their $500 Recepter Radio HD is finally shipping. They must be ecstatic to get out first: it's been a difficult race. Radiosophy should be shipping their $270 system soon; Polk Audio may not ship their full-feature $700 system until late winter.