Some decent, self powered speakers running directly from her TV audio outputs would probably be the most simple way to achieve a better stereo sound. She would have definitely improved (albeit not perfect,)sound and still only have to deal with her TV remote for volume.
If she wants 5.1 sound without complexity, I'm in the "Soundbars are useless" category. I have heard 4 different installs of them and only the one that was professionally calibrated gave the slightest illusion of surround sound and they all suffered from a lack of bass. The self calibrated ones not only had no surround effects but also sounded somewhat 'unnatural'.
I think they even sounded less natural than TV speakers in my opinion because the sound drew attention to itself. At least you tend to forget about the crappy sound from TV speakers as your ears and mind adjust to it. Perhaps it was just the mental fact that I was aware of the bar but after watching full movies, I was still distracted by the unnatural sound.
