I have a really nice yamaha home theater system. It is a 5.1. Anyways, I was wondering what kinda effect the system would have if I took 2 speakers off a random stereo and connect them up to the empty ports on the receiver. I am guessing they would be either L&R surrounds or fronts. They are pretty old speakers... so would it be worth it to throw them on for a dvd shindig, or would it take away from the other speakers and make it sound like shat?