GDAM supports hardware input in a few ways. Midi devices, auxilliary keyboards, and ultrasonic rangefinder input plugins exist already. As of writing, only gui components make use of hardware input, but it is implemented on a lower level, so other clients may support it in the future.
You can get started immediately: open the midi selector and then open a gain widget. It should have a MIDI button once the selector is opened. Depressing that button with the mouse, which wiggling a midi knob will automatically attach the gain's volume to the knob.
You can also specify more information about your device. Then the messages will be more readable, and that is the only way to trap "System Exclusive" messages.
NOTE: hardware input has been rewritten as of version 0.922. Changes include unification of hardware input methods, and the ability to assign a set of bindings to a component by reading an xml file.
GDAM supports midi hardware input. Through plugins, other hardware input devices (i.e. sonic rangefinders) can be supported. Hardware input devices are cool because they transcend the clumsy mouse-and-keyboard interface most computer users suffer. For instance, midi sliders allow a user to vary several parameters simultaneously. Also, hardware input assignments don't obey window focus the way a computer's normal keyboard does, and will continue working regardless of what application the user may be mousing around in. Additionally, hardware input devices allow the operator to spend less time hunched over a monitor.