Logitech® Speaker System Z623. For big, bold, 2.1 sound. THX® Certified means quality you can count on - these speakers have met strict performance standards to achieve THX certification. You'll hear - and feel - immersive audio from 200 watts (RMS) of power that brings music, movies and games to life. Multiple inputs, as well as a built-in headphone jack, make it easy to get great sound from up to three audio devices. Easy, two-satellite setup and a powerful subwoofer give you big sound - even in large spaces. And integrated controls put you in command: dial the volume and bass up or down to customise your listening experience.