The downside as always with early adopters is that you can't hear it. There aren't any radio receivers for 5.1 channel surround sound yet. That didn't' stop them from showing it off at the last NAB conference though. As of April 2007, 100.7 WZLX in Boston is the first American radio station to broadcast in 5.1-channel surround sound on its HD channel.
To broadcast multi-channel sound on its HD radio signal, WZLX uses the new MPEG Surround technology provided by Fraunhofer IIS. This new MPEG standard allows broadcasters to switch from stereo to surround sound smoothly. The build was done with help from from Telos Systems and Fraunhofer.
WZLX has been serving Boston since 1948. That 100.7 stick then owned by the original WBZ. they were an early IBOC adopter adding an HD2 sub channel in 2006. It was programed as a deep catalog Classic rock channel branded as “deep cuts.”