Subwoofers or subs are responsible for the lowest frequencies in your home theater system. The audience should actually feel the subwoofer on a good home theater system.
In extreme cases, the subwoofer can ruffle the pant legs. The best subwoofers should make the room shake, rattle drinks, frighten small children and animals and communicate with whales. Okay, maybe we're getting carried away with the power of a subwoofer, but this isn't far off.
Since the subwoofer provides the impact of a home theater system, the most powerful amp in your home theater should power the subwoofer. You want the audience to feel as if they've been pushed back into their seats with the power of your subwoofer.
The only concern you might have with the placement of the sub is experimenting with its placement relative to nearby walls, especially if this is a ported sub. A sub placed in a corner might be robbed of its dynamic range. The sub might sound boomy and miss out on its potentially tight, accurate bass. Corner loading (placing your sub in the corner of a room) is often considered desirable for home theater as it can augment a range of very low frequencies through a room.