Nabu Casa’s Home Assistant Connect AUX-2 goes on sale 11 November for $69 (€59) and plugs old hi-fi amps and serial gear into Home Assistant. The company calls it “a smart home multi-tool that makes the devices you already own smart”.
The serial side is the clever part. Serial (RS-232) is a two-way connection over a single cable, and it’s still found on plenty of older amplifiers and receivers. Nabu Casa says serial control doesn’t rely on the cloud, so it keeps working after a service shuts down and your data stays in your home.
The most sustainable device is the one you already own. No device should be left behind because it doesn’t have smart capabilities, or worst of all, its cloud services get turned off.
Paulus Schoutsen, founder of Home Assistant
The AUX-2 has two RS-232 ports, and it supports Modbus devices with an inexpensive USB adapter. Over serial, the AUX-2 can turn up the volume, get an energy reading, or wake a device from standby. Many classic amplifiers and receivers have both an optical input and a serial control port. Connected to both, the AUX-2 delivers lossless audio and controls volume, source, and power.
That’s where Music Assistant comes in, a free, open-source app that plays nearly any streaming service or local files on almost any smart speaker. Nabu Casa’s example is Spotify, Tidal, or local FLAC files playing on an old hi-fi, synced with HomePod and Sonos speakers around the house. The company even pitches it for TVs: block the set’s spyware, control it through the AUX-2, then block it from phoning home.
The box also takes on a few other jobs:
- It can replace a Bluetooth hub, connecting Bluetooth smart devices directly to Home Assistant.
- It connects a Z-Wave adapter over the network, and its USB port lets modern devices plug in.
- It runs on Power over Ethernet, or on USB-C power with Wi-Fi.
- Home Assistant finds it on the network, and a setup wizard walks you through each feature.
Tinkerers get room to play. The AUX-2 runs ESPHome with an unlocked bootloader and has a Grove port for adding sensors, and Nabu Casa will release its PCB and 3D-print files.
Nabu Casa makes all official Home Assistant hardware, and it recently renamed Home Assistant Cloud as Link and planned a successor to its Green hub. Home Assistant runs in more than 2.7 million households, according to the company, and it’s governed by the Open Home Foundation, a Swiss non-profit founded in 2024. Nabu Casa says it takes no VC money or private equity, and it gives the majority of its profit to the foundation.
No independent testing exists yet. Schoutsen expects the community to keep finding new uses for it, because it’s fully open.
