Just got a used Boston Acoustics DT7000. After hooked up and use the remote to hit the "test tone" button. All the front, center and rear speakers has pink noise to go around. But, when I hook up a dvd through the coaxial digital connection to watch a Dolby Digital movies or concert, sound from front, center and sub are very good, but there are no sound from the rear surround channel. Do you think there is something wrong with the circuity inside?