Electrum Drum Machine / Sampler (îáíîâëåíî v 4.8.4)

You can now use external USB MIDI controllers to play Electrum's pads. They are also velocity sensitive.
See MENU->MORE->PLAY pads with USB MIDI
You must use an OTG USB cable to use host mode!
So far this has been tested and works on Galaxy Nexus, Galaxy Tab 10.1, and Motorola XOOM.
Testing was done with an Akai LPD8 Midi controller, using a USB-B to Micro USB OTG cable bought on Amazon.
You should be able to even use a USB MIDI keyboard and just map the keys to Electrum's pads.