Hi there. I have a rMBP 15" that I run Logic Pro 9 on. I'd like to get a small, cheap midi keyboard but I'm not sure which direction to go. I have maxed out my two USB ports: I have a Scarlet 2i2 via USB, and a USB 3 hard drive for audio files, etc. I see USB MIDI keyboards out there but I'm not sure if I degrade throughput at all if I add a USB hub to this mix. Can anyone suggest any recommendations?