Stereo 3.7W Class D Audio Amplifier - MAX98306 is surprisingly powerful - able to deliver 2 x 3.7W channels into 3 ohm impedance speakers. Inside the miniature chip is a class D controller, able to run from 2.7V-5.5VDC. Since Stereo 3.7W Class D Audio Amplifier - MAX98306 is a class D, it’s incredibly efficient (over 90% efficient when driving an 8Ω speaker at over a Watt) - making it perfect for portable and battery-powered projects. It has built in thermal and over-current protection but it barely gets hot.
The inputs of Stereo 3.7W Class D Audio Amplifier - MAX98306 go through 1.0uF capacitors, so they are fully 'differential' - if you don't have differential outputs, simply tie the R- and L- to ground. The outputs are "Bridge Tied" - that means they connect directly to the outputs, no connection to ground. The output is a 360KHz square wave PWM that is then 'averaged out' by the speaker coil - the high frequencies are not heard. All the above means that you can't connect the output into another amplifier, it should drive the speakers directly.
Stereo 3.7W Class D Audio Amplifier - MAX98306 comes with a fully assembled and tested breakout board with 1.0uF input capacitors. Headers are also included to plug it into a breadboard, 3.5mm screw-terminal blocks so you can easily attach/detach your speakers, and a 2x4 header + jumper to change the amplifier gain on the fly. You will be ready in 15 minutes. Speakers are not included, but you can use any 3ohm or greater impedance speakers.
Adafruit Web Site: http://www.adafruit.com/products/ 987