The BT913 Controls up to 4 pairs of loudspeakers connected to one stereo amp. Also has a headphone socket for monitoring. 4mm gold plated sockets accept banana plugs or bare ended speaker cables. The BT913 employs a special Parallel and Series switching circuit to protect the amplifier. Regardless of which loudspeakers are switched on, the amplifier load will not fall to less than half that of the loudspeakers in use. If using 8 ohm loudspeakers the minimum load will be 4 ohms. Nearly all amplifiers will accept a load of 4 ohms. • 200 Watts per channel. • Headphone socket with amp protection. • Accepts cable up to 6mm in diameter. • Screw terminals ensure solid connection. • Using headphone socket doesn’t mute speaker sound. Silver plated switch contacts. Gold plated terminals. Suitable for 4mm Banana Plugs. Using headphone socket doesn’t mute speaker sound.