With Kontrol S4 (MSRP: $999, pictured above), Native Instruments has developed its most ambitious entry into the DJ game to date. Essentially a physical extension of NI's Traktor software, the S4 integrates four-deck control with a four-channel digital mixer and audio interface. It's bundled with its own unique version of Traktor Pro, designed specifically for the S4; essentially, this is an all-in-one DJ solution that takes much the same approach to hardware/software integration as NI's Maschine, and shares many of its design sensibilities. While it lacks the tank-like metal construction of a high-end turntable or mixer, it's a very well-crafted unit.
Where the S4 excels is in letting the user get endlessly creative with sampling, setting up cue points, and creating loops on the fly. Within 15 minutes, I was remixing tracks in real-time in a way that would be impossible with lesser hardware, and there's an elegant consistency to the user interface that makes things as intuitive as possible. Recording, playing, and changing the size of samples, adding and manipulating FX, and juggling loops rarely requires you to look up at the computer, and the full hardware control (including independent knobs to control both the size and position of loops) allows for some amazing creative freedom.
Of course, all of this getting freaky requires your tracks to be beat-matched, and this is where digital solutions tend to fall short. Traktor has excellent beat-detection algorhythms, and when you're matching two songs with distinct beats, it's pretty smooth sailing: sync the incoming track, nudge it a bit with the jog-wheel to get them in line, and you've got a locked mix to go crazy with. When you need to manually beat match, the S4 lets you do so; the jog wheels have a nice weight and sensitivity, and scratch DJs can channel the wiki-wiki gods despite their small size. But these are not "active" platters, and if you're used to mixing actual spinning records with plenty of torque, getting used to mixing with two inert jog wheels will definitely take some getting used to.