Hi, I am thinking of upgrading my Logitech X-530 speakers to a Yamaha YHT-160 HTIB. I noticed my Logitech speakers have two 2 inch drivers in each of the 5 satellite speakers. What is the advantage of having two of these? Do most speakers have more than one driver, and does the Yamaha have more than one driver? Will I notice a major difference between speakers with one driver and speakers with more than one driver? Sorry for my noobish questions, I'm learning.