Apollo CAST-1 audio streamer integrates with Music Assistant

The Apollo CAST-1 is a new ESPHome-based audio streamer retailing at $34.99 that brings local smart home control to existing powered speakers, soundbars, and amplifiers without requiring a cloud account. SmartHomeAssistant reported that the device connects via a 3.5-millimeter line-out and integrates directly with Home Assistant and Music Assistant.

ESP32-S3 Microcontroller Powers the Audio Streamer

The streamer measures 45 by 45 by 15 millimeters and houses an ESP32-S3 microcontroller equipped with 16 megabytes of flash memory and 8 megabytes of PSRAM. For audio processing, the unit relies on a Texas Instruments PCM5122 32-bit digital-to-analog converter that delivers a signal-to-noise ratio of 112 decibels and an analog output featuring a 2.1 VRMS full scale. SmartHomeAssistant noted that the hardware setup requires a separate 5-volt USB-C power supply and appropriate cabling, as neither a power brick nor connection wires are included in the box.

CAST-1 Connects to Home Assistant via Wireless Networks

Out of the box, the CAST-1 arrives with pre-flashed firmware, removing the need for initial flashing procedures. Users can connect the device to a 2.4-gigahertz wireless network either by opening a fallback hotspot via a smartphone or laptop, or by utilizing Improv over Bluetooth directly from Home Assistant if a nearby Bluetooth proxy is available. Once connected to the local network, the device appears under devices and services within Home Assistant, where the ESPHome integration manages firmware updates. SmartHomeAssistant tested a test unit running firmware version 26.8.26.7, which updated directly within the platform to version 26.9.21.1.

Multiroom Audio and Text-to-Speech Performance

When integrated with Music Assistant, the CAST-1 automatically populates as a player via mDNS. The device creates two distinct media player entities upon connection. The primary Apollo CAST-1 player handles text-to-speech announcements, alerts, and conventional media playback, while the Apollo CAST-1 Sendspin player acts as the designated target for Music Assistant and multiroom grouping. SmartHomeAssistant observed during testing that pairing the streamer with a living room television yielded no audible synchronization delay, whereas grouping a Google Nest speaker into the same zone introduced a slight lag due to Google’s proprietary handling of Cast web applications.

For household automation, text-to-speech announcements trigger a 40-decibel ducking effect on active music playback, allowing the notification to play clearly before smoothly fading the audio back to normal volume within approximately one second.

Optional Ethernet Module Provides Wired Network Connection

Beyond the core unit, the manufacturer offers supplementary hardware. An optional W5500 Ethernet module mounts directly onto two rows of pin headers on top of the enclosure to provide a wired network connection without requiring soldering or firmware reflashing. SmartHomeAssistant pointed out that this module handles data transmission only, meaning power must still be supplied via the USB-C port. The onboard Bluetooth switch functions as a proxy for Bluetooth Low Energy sensors and trackers rather than receiving audio streams from mobile phones, though the manufacturer has announced intentions to develop a Squeezelite firmware supporting Bluetooth audio.