Besides audio interfaces, as already discussed, there is of course a whole range of hardware that can be involved in the production and mixing process. For example: effects units, mixers, controllers and electronic instruments. Most relevant to mixing is the control surface. This is a device with sliders, knobs and buttons, which give physical control of the DAW. It means, for example, that you can move faders as you would on a mixing desk, and the software records your gestures, and replays the mix, using ‘automation record’.
One hybrid system, which is not itself a DAW, but is worth mentioning purely because of how accessible it is, is Komplete Kontrol, from Native Instruments. This is a combination of a music keyboard with software that allows speech access to the thousands of sounds in its library. You can find more here: