The PRO DJ LINK stem engine ●
PRO DJ LINK and stems.
Finally on the same rig.
A Raspberry Pi 5 sidecar that runs pre-extracted stems locked sample-accurately to your CDJ-3000X, without ever taking PRO DJ LINK offline. Stacked waveforms intact. Beat sync intact. Vocals and instrumentals, finally, on the same rig.
Stock Pioneer software splits your rig into two mutually-exclusive modes. You get everything on one side or stems on the other, never both. The CDJ-3000X (Sept 2025) doesn't combine native stems with this mode either. As of this writing, no shipping firmware merges the two.
CDJs play their own audio from a Rekordbox-exported USB. Rekordbox software is offline.
Rekordbox is the audio engine. CDJs drop to HID controllers. Audio is Mac → DJM USB.
Pioneer makes you choose.
● CHURRDJ doesn't.
CHURRDJ keeps your CDJs in Export mode (PRO DJ LINK stays online) and parallel-plays pre-extracted stems from a sidecar Pi, routed through additional mixer channels. The Pi locks to the CDJs over the LAN, keeping its stem cursor matched to whichever deck is playing.
< 1 ms drift
A sub-sample sync loop keeps each stem locked to its CDJ's pitch fader in real time. Move the slider; the stem follows.
1 swap per track-load
Load a new track on a CDJ and the Pi reads the metadata, looks it up in your stem index, and swaps the channel's playing stem cleanly, mid-set.
Zero install
The engine serves a token-gated control page. Open it on any phone or laptop on the LAN (or via Tailscale) to toggle vocals/instrumental and record the master mix.
CHURRDJ is built for Pioneer booth gear and validated on the reference rig below. Stem playback runs across the Pioneer USB-DJM family. Master recording supports that same family, but the DJM-A9 is the only mixer we've tested on hardware so far, so recording on the others is experimental for now.
Source units running PRO DJ LINK
Any DJM with USB audio output
Tested on the DJM-A9; other Pioneer DJMs experimental
What the engine + sidecar run on
CHURRDJ has been proven on real Pioneer rigs, on real gigs — working DJs ran it in the booth and told us exactly what to tighten in the setup flow and the live UX. It's dialed in, and now it's available as a finished product.
CHURRDJ now ships as a preconfigured, ready-to-go unit — assembled, imaged, and bench-tested against a live CDJ + DJM rig before it leaves San Jose. Plug it into the booth and the stems are already there. Pre-order yours now.
$649 · Preconfigured, ready-to-go unit.
Built to order in San Jose and bench-tested before it ships. Ships worldwide — shipping calculated at checkout. Secure your unit now.
Rekordbox doesn't expose a stems extension point, and the architectural problem isn't "can stems run" but "can stems run while PRO DJ LINK stays alive." Stock Rekordbox makes those modes mutually exclusive. CHURRDJ sidesteps the whole conflict by running stems on a separate audio device (the Pi → DJM USB) while the CDJs stay in Export mode untouched. There's no way to do that inside Rekordbox.
Stem playback is designed to work with Pioneer DJMs that have a USB audio output: the V10, 900NXS2, 750MK2, and 450. Master recording now supports that same Pioneer DJM family, but the DJM-A9 is the only mixer we've tested on hardware, so recording on the others is experimental for now. We confirm compatibility with the rig you list when you order. Non-Pioneer mixers are not supported.
Pi 5 (4 GB or 8 GB) is the reference target, and the booth image is built for it. Pi 4 should be powerful enough but isn't validated. Pi Zero won't keep up with the real-time sync work under realistic loads. If you run CHURRDJ on a Pi 4 successfully, we want to hear about it.
$649 plus shipping for the complete, preconfigured unit: the sealed engine, a backup system card, the full cable kit, a spec-matched power supply, the quick-start card, and lifetime signed firmware updates. Built to order in San Jose. US shipping is $20, international $50, calculated at checkout. Import duties and VAT on international orders are the buyer's responsibility.
Pre-orders are estimated to ship by late July 2026. Each unit is assembled, imaged, and bench-tested before it leaves the bench. Every unit carries a 30-day rig guarantee: if it won't run on your supported Pioneer setup, you get a full refund.
You don't run anything by hand. Drag a track onto the CHURRDJ Ingest Mac app and it does the rest: it splits the song into vocals and instrumental (on-device, Apple Silicon recommended), matches it to your library, and ships the stems to your booth automatically. Add tracks any time; they process in the background. The Mac app is a free companion download for owners.
Yes, the engine looks up tracks by Rekordbox metadata broadcast over PRO DJ LINK. Source audio files have to exist on disk (no Tidal/streaming-only tracks). Indexing is automatic: the Mac app rebuilds the lookup whenever you add music, so newly added tracks just work.
No. The engine and sidecar run fully offline once stems are on the Pi and the engine is configured. Internet is only useful for remote phone control via Tailscale (which lets you reach the Pi from your phone over its mesh VPN even when the venue Wi-Fi blocks client-to-client traffic). Offline-only setups work; you just have to be on the same LAN as the Pi to load the control page.
Probably, the PRO DJ LINK protocol has been stable since the CDJ-2000NXS2 generation. Our sidecar reads PRO DJ LINK directly and has been updated specifically for the CDJ-3000X. If a firmware update breaks something, we treat it as a priority and get a signed patch out to every unit quickly.
Yes. The engine captures the master out over USB and writes a 24-bit stereo WAV to a folder you choose. The DJM-A9 is fully tested; recording on the other Pioneer DJMs (V10, 900NXS2, 750MK2, 450) is supported but still experimental, so tell us how it goes. Press Record in the web UI to start. It is off by default and writes about 0.9 GB per hour, so leave room on the Pi's storage.
Something not covered here? Write to beta@churrdj.com, we'll add your question to the next pass.