I first used these apps on an iPad 2, which worked perfectly. Meanwhile, I have an iPad Air, for which I just need a small apple lightning-to-30pin adapter to use the same equipment, and it works perfectly, too.

You need a compatible usb-midi interface. There are various ones you can use with the iPad, I use a better one called iconnectMidi2+.
http://www.thomann.de/gb/iconnect_midi_2.htm
It comes with an iPad(30pin)-to-USB cable, which you plug into the interface. On the other side of the interface there are 2 DIN midi-ins and two midi-outs. This way you connect your keyboard (midi in) and the SD1000 (midi-out). You just have to pay attention which one of the two outs/ins you use so that a double midi signal (directly from keyboard to SD1000 plus indirectly via iPad) is avoided. That's all. Very portable and quite easy.