The Logitech Z313 is a good, compact, easy-to-setup subwoofer with powerful, room-filling, balanced sound.  I bought at Best Buy, opened it for the first time to take a photo now and checked for serviceability.  To set up, simply connect the speakers to the subwoofer and connect the subwoofer to the computer, the control box makes it easy to operate.  50 watts peak.  Buy this speaker system and use it for many years!  Thank you!