MIDI controller
A control surface that sends MIDI (and increasingly USB) to play and shape other instruments, generating no sound itself — keys, pads, faders, and encoders as the human interface to software or hardware synths and DAWs. It is the input end of the signal chain: distinct from a synth (which makes the sound) and an audio-effect-plugin (which processes it). The nearest relative is the chord synth, which shares the “interface as the point” idea but does make its own sound (and a chord synth with MIDI-out, like the Minichord, straddles both).
Why it belongs here
The spoke keeps circling the question of who moves the controls — patched automation (modular-routing), the environment (cyma-forma-alt‘s sensors), or hands-only (music-from-test-equipment). A MIDI controller is the most literal answer: dedicated hardware whose only job is to translate hand movement into control data.
Two shapes: keys vs knobs
The spoke now has two, and they sit at opposite ends of the controller idea. keylab-mk3 is a keyboard controller — you play notes, and it’s sold bundled with software instruments (see below). OXI E16 is a knob box: 16 endless encoders, no keys, built to grab and morph parameters on gear you already own (192 mappable CCs across scenes/pages). The E16 also blurs the “generates no sound itself” line in an interesting way — its knob recording and firmware-1.0 MIDI looper record and replay control gestures, so it authors performance data rather than just passing it through, pulling a pure controller toward the sequencer end of the chain (fitting, since oxi-instruments is a sequencer maker).
The bundle economics
Controllers are often sold bundled with software instruments (KeyLab ships Analog Lab / V Collection / Live Lite), so the hardware doubles as distribution for a maker’s synth software — a different business model from the standalone free plugins in audio-effect-plugin, and also from the standalone premium E16 (€449, no bundled software; the value is the control surface itself). DAW-integration depth and control-surface protocols (MIDI vs proprietary DAW modes) are the natural next things to page as more controller sources arrive.