Midi Piano allows you connect and interact with MIDI devices through a friendly UI, and can be useful for testing or even playing your digital instruments. You can connect a MIDI keyboard as an input device or use the app itself as an instrument (via UI or PC keyboard). Then you can set either Microsoft GS Wavetable (to play the sound on your PC) or an external device as the output.

The UI also offers a list of instruments based on General Midi, and a Pad Array for drums that you can manually configure. You can also see MIDI messages being received from the input device and both the keys and the pads will give visual indication when notes are being played.

Note: Have in mind that Microsoft GS Wavetable has to be available and working properly in order to reproduce sounds directly on your device. The presence of some other MIDI software might interfere with this app.