Granular synthesis and MPE are a natural pairing, and one of the more interesting examples has just reached its final form. Delta Sound Labs has released Stream Pro, the MPE-compatible live granular synthesizer that was shown at NAMM 2026 under the working name XStream. It is out now at $99 for macOS (Apple Silicon and Intel), Windows and Linux.
From the Stream effect to a playable instrument
Stream Pro is built on the engine of the company's 2020 Stream effects plugin, but it is designed as an instrument you play rather than a processor you feed. You can sample live directly into the plugin or drag and drop your own audio, and then shape that material in one of two modes.
Single mode turns the buffer into continuously evolving textures, the classic granular "cloud." Multi mode maps samples across the keyboard with a polyphonic grain engine, eight independent playheads, velocity sensitivity and full MIDI tracking. For anyone who has found granular tools hard to play expressively, Multi mode is the interesting part: each note can have its own grain behavior.
Where MPE fits in
Stream Pro lists MPE, velocity and four multi-wave LFOs as modulation sources, routed through a simple mod matrix. In practice that means per-note pressure, slide and pitch gestures can steer grain parameters independently for every voice. Pushing one finger harder can thicken a single grain stream while the rest of a chord stays calm. If you have a controller such as a LinnStrument, an Osmose, or a Seaboard-style surface, that kind of per-finger control is exactly what granular engines have been missing.
Each grain or voice also gets its own effects chain, covering grain level, distortion and spatial motion. Delta Sound Labs' earlier announcement also described analog/digital-style distortion, a texturizer with drive and ladder filter, and tape delay with feedback.
Spatial motion as an expressive target
The other headline feature is a built-in 3D spatialization engine that positions sound in the stereo field, with orbit, drift and randomized motion paths. The January announcement mentioned Steam Audio HRTF processing and stereo or surround placement. Because movement is applied per voice, spatial position becomes one more thing a performer can shape, not just a mix decision made afterwards.
Formats, price and what changed
The October release lists VST3, AU and AAX, where the January preview mentioned only VST3 and AU, so Pro Tools users are now covered. The price is $99; the introductory $79 offer mentioned earlier in the year applied to the original launch window. Check the product page for the current offer and demo availability.
Our take
Granular plugins are plentiful, and one reviewer has already called Stream Pro "another granular plugin among many." That is fair. What sets it apart is the focus on live performance: sampling on the fly, polyphonic playheads and per-voice spatial movement, all reachable with MPE gestures. If you mostly use granular tools for static pads, you may not need it. If you want to play grain clouds with your hands, it is worth a demo.
A practical tip for any MPE granular instrument: set your controller's pitch-bend range to match the plugin, keep slide (CC74) mapped to a parameter you can hear clearly, and start with a short, harmonically rich sample. Grains reveal subtle gestures far better when the source material has some movement of its own.
Sources: Synth Anatomy, Delta Sound Labs.