As opposed to the SX/SX2, which is a stand-alone mixer too, the SR does not have the features of hooking up external gear. There IS an aux input, but that is purely for backup purposes. Hook up your iPhone/iPad/iPod here with a mix ready to go in case of (computer) trouble.
Even on an SX (or just about any other controller with stand-alone mixing capacity) you cannot hook up CDJs and play them THROUGH Serato! They would just be analogue sources that you add to your mixer, totally separate from Serato. So none of the features like FX available. The SX2 does allow to hook up CDJs in that fashion and use them as Timecode controllers. But you’d be needing Timecode CDs and such.
Serato does support HID-control for selected Pioneer CDJs I believe. So it should be possible to hook up your CDJs by USB to your laptop, assign two decks to them and run the sound back through the controller. This would be full Serato control, including loops, cues, beatgrid, fx and such. Setting FX and EQ through the controller, all the rest primarily on the CDJs.
The other option with the SR would be to get an external soundcard and use that to get Timecode control while setting your sound output for your TC decks to the controller.
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