It may depend on which amplifier you have. With our Samsung HT-X20 (a discontinued bottom feeding unit), the USB port is useless for anything other than unknown Chinese devices. There are also no audio inputs to allow running the TV sound through the stereo speakers. You may have to connect your computer directly to the TV set.
Consult your manuals for the stereo and TV for more information. If I could find a better stereo that would fit in the confines of the cabinet, I'd replace mine. Unfortunately, when the thieves stole the TV's, they left it. Must have been smart crooks.