This Bonnet uses I2S a digital sound standard, so you get really crisp audio. The digital data goes right into the amplifier so there's no static like you hear from the headphone jack. And it's super easy to get started. Just plug in any 4 to 8 ohm speakers, up to 3 Watts, run our installer script on any Raspberry Pi, reboot and you're ready to jam!
We sure love the ATmega328 here at Adafruit, and we use them a lot for our own projects. The processor has plenty of GPIO, Analog inputs, hardware UART SPI and I2C, timers and PWM galore - just enough for most simple projects. METRO Mini is the culmination of years of playing with AVRs: we wanted to make a tiny, breadboard-friendly development board that is easy to use and is hacker friendly. Metro Mini can be programmed with the Arduino IDE (select 'UNO' in the boards dropdown)
The Adafruit Feather nRF52 Pro ships pre-programmed with the Mynewt serial bootloader that allows you to flash firmware to the device directly from the command-line using the on-board USB Serial converter and the 'newtmgr' tool, so you can get started right away with no additional hardware required. For more advanced debugging, however, you can use a Segger J-Link and the on-board SWD debug connector, which gives you access to a more powerful set of development tools and options.
Breathe easy - we finally have an I2C VOC/eCO2 sensor in the Adafruit shop! Add air quality monitoring to your project and with an Adafruit CCS811 Air Quality Sensor Breakout. This sensor from AMS is a gas sensor that can detect a wide range of Volatile Organic Compounds (VOCs) and is intended for indoor air quality monitoring.