To celebrate my 50th Key Secrets column, here’s one of my favorite tips; using a powered USB hub to connect multiple MIDI controllers to an iPad. In the photo, a Korg nanoPAD2 is playing Drums XD on MIDI channel 1, a CME Xkey is playing Photophore strings on channel 2, and a Keith McMillen QuNexus is playing Propellerhead Thor bass on channel 3. Each controller is optimized for the sound it’s playing. (Turn on Background Audio in your apps to enable simultaneous control.) A Monoprice USB battery pack powers the hub, allowing it to run an old Edirol UA-20 audio interface as well ($15 on eBay), adding stereo I/O plus a dedicated headphone jack.