Delta Sound Labs XStream: A Granular MPE Synthesizer With 3D Spatial Audio

Announced at NAMM 2026 and released in April, XStream from Delta Sound Labs is one of the more technically ambitious MPE instrument plugins of the year. Built as a spiritual successor to the company's Stream granular sampler, XStream moves beyond its predecessor by fusing a full granular synthesizer engine with deep MPE integration and a 3D spatial audio system — all in a single plugin priced at $79 (introductory) / $99 regular.

For musicians who work with MPE controllers, XStream represents an interesting proposition: a granular instrument where physical gesture doesn't just shape timbre but also manipulates space.

Dual-Mode Granular Engine

XStream operates in two distinct modes. In Single mode, any loaded sample becomes the source material for evolving pads and textures — granular processing fragments the audio into overlapping grains, each controllable in size, density, pitch, and position within the sample. This is the classic granular pad territory: lush, layered, atmospheric.

Multi mode is where MPE becomes particularly relevant. Here, XStream transforms samples into a fully playable polyphonic granular synthesizer, with MIDI tracking and polyphonic grain engines per voice. Each MPE note spawns its own grain cloud, with per-note pitch bend, pressure, and slide available as modulation sources. Press a key harder and the grain density increases. Slide a finger and the playback position scrubs through the sample. Release slowly and the grains fade independently per voice rather than cutting off in unison.

This creates a texture vocabulary that standard granular processing — and standard MIDI — simply can't replicate.

Per-Voice Effects Chain

One of XStream's more distinctive features is its per-voice effects architecture. Rather than applying effects globally to the output, each individual voice (each granular stream) gets its own effects processing:

Per-voice distortion with analog and digital character modes
Texturizer combining drive, a ladder filter, and a tape delay with feedback

This means that a chord played through XStream can have each voice saturating and filtering at different rates, depending on how much pressure is applied per finger on an MPE controller. The result is a kind of independent timbral evolution across voices that's difficult to achieve with a standard insert effects chain.

3D Spatialization with Steam Audio

The spatial audio engine in XStream uses Steam Audio's HRTF (Head-Related Transfer Function) technology to position individual grains in three-dimensional space. Each grain or voice can be placed and animated in a 3D field using built-in motion paths: orbit, drift, and randomized motion. With headphones and MPE control, the result is audio that moves through space in direct response to physical gesture — a different kind of expressiveness than timbre alone.

Live Recording

XStream also supports live sample capture with overdubbing, allowing you to record audio directly into the plugin's sample buffer and immediately begin granular processing it. For live performers and sound designers who work with real-time input, this turns XStream into a live granular processor as well as a sample-based instrument.

MPE Integration

XStream handles all three MPE dimensions — per-note pitch bend, pressure (CC 74), and slide (Y-axis) — with configurable routing in the plugin. It works in any MPE-capable DAW including Bitwig Studio, Ableton Live 12, Logic Pro, and REAPER. It pairs particularly well with controllers that excel at sustained expression like the Haken Continuum Slim 21 or the Expressive E Osmose CE, where slow pressure changes and lateral slides translate naturally into granular density and position modulation.