I don't know if this is magnetically shielded, but unless you are using and older CRT TV, one of those with a glass tube, then you don't need any magnetic shielding. As for ideal distance, there really isn't one. The reason you can get away with one sub in a home set-up is that most rooms in a home aren't large enough for you to be able to hear where a low sound comes from. Higher notes can be located by our ears, which is why you need multiple smaller speakers to localize those sounds, but low notes cannot be in a small room, so you just need one sub. Ideal placement of that sub has more to do with your room shape, furniture layout and listening position. With a sub like this one, you can really get away with putting it just about anywhere in the room; even under a table or in a corner.