Logitech Z-640, 5.1 channels, 71.2 W, 75 dB, 45.5 W, 25.7 W, Wired Logitech Z-640. Audio output channels: 5.1 channels, RMS rated power: 71.2 W. Signal-to-Noise Ratio (SNR): 75 dB. Satellite speakers RMS power: 45.5 W. Subwoofer RMS power: 25.7 W. Connectivity technology: Wired