MidiStation

The main section (the upper one) where you can set the transmitting channel, the program and the volume for 4 different VST instruments (or for 4 instruments in a multitimbral VSTi) and you can change the playing instrument simply moving a knob or a slider on your midi keyboard sending a specific Control Change number (CC # 83 is the default one, but you can choose another one from the drop list in the up left corner of MidiStation): values 0, 42, 84 and 127 correspond respectively to instruments A, B, C e D;

The zones section (the lower one) where you can choose the playing instrument(s) through the buttons on the left and set for each one the notes range (through the "low limit" and the "high limit" drop lists, transpose them of +/- 3 octaves and determine if CCs (sustain pedal, modulation wheel, pitch bend, etc) are filtered or not. So you can create split or layering situation involving two or more of the 4 instruments.