Whenever I try to use a digital input with DD surround sound, I can only get Downmix stereo audio. Also, when listening to FM stereo, none of the simulated surround options are availlable (accessed through the surround button on the front). I would rather not bring in my unit to a repair shop as it will probably cost me more than what my T753 is worth. However, I would like to repair it and keep it myself. (I am an EE). Anyone have this problem before or have an idea of what to look at (Surround sound board), schematics, replacement boards? Thanks.

Audio Players & Recorders - NAD - T753 Receiver