Toward the right, you've got the USB type B connector that runs to your laptop, the AC adapter jack, and the master power switch.

ENGADGET: Native Instruments Traktor Kontrol S4 review Alt

Yes, that's right, we said AC adapter jack: unlike the X1, the S4 can't be driven off bus power alone, unfortunately.

ENGADGET: Native Instruments Traktor Kontrol S4 review Alt