3.5 mm audio out is generally a 3rd rate audio output option for driving low wattage speakers. To get a dolby digital passthrough you need an optical out/coaxial/ARC enabled hdmi port. Also the tv decodes dolby digital to stereo mode to play through left and right channels,mostly the same stereo l&r output goes through the 3.5 mm, simply not enough to drive a 2.1,and without any control on crossover or amplification results will be abysmal.