The hardware setup for this build is fairly straightforward. The ESP8266 (I used Adafruit's Feather HUZZAH) is connected to a VS1053 decoder chip with the SPI bus. The VS1053 is connected to a small powered speaker (I just used one I already had laying around). The speaker and feather are connected to a battery - the VS1053 is powered by the Feather's voltage regulator. The Analog 0 pin on the Feather is tied to ground, which signals to the Ka-radio software that there is no front panel.

Unlike the schematic, my speaker driver board has left and right channel inputs - but it only has a single speaker.