I want to buy a set of 2.1 speakers for my pc, but I don't have enough room on my desk for a big sub woofer. But because my pc is on a corner desk there's is plenty of room behind the my 24 inch monitor for a sub woofer, however is it a good idea to put it there? Will putting a sub woofer behind a monitor negatively affect the sound in any way? I don't think putting it on the floor and underneath my desk would be a better idea?