A fully self contained, USB powered ~5W PMPO¹ Class-D amplifier inside a Speakon connector.
This adapter allows you to connect your phone / laptop / $USB-audio-host-capable device to any passive loudspeaker that accepts a Speakon plug.
In my tests it reached volumes significantly above "room volume". Its output power is probably enough to host a small indoor party.

The mechanical dimensions of the PCB and the insert were designed for a (now discontinued) Neutrik speakON NL4FX.

The .step file can be found in the root of the repo and the full design is on OnShape.

(Not really issues, as this project is more of an irl shitpost, so any issues are more or less by design :D)

• Android phones produce less volume than PCs. Idk why exactly, but it appears to be a software limitation, it's not limited by USB power.
  • On some Android phones it's way too quiet though, there you can use this shady volume booster app that actually manages to increase the output volume in that case.
• The project was designed for the now discontinued NL4FX. It is unclear if it would mechanically fit inside the new NL4FXX.
• v0.1 has a 3225 footprint for a 6MHz crystal. No 6MHz crystal is available for that footprint tho.