I seem to often have a need to test small speakers, but audio sources these days tend to expect the speakers to have their own amplifier built-in. Rather than always having to hijack some other system and rig up appropriate amplifiers and wiring I decided to make a small test device that can directly drive speakers as low as 4 ohms. Originally, I was just going to build an amplifier, but I found an MP3 player with built-in amp for a ridiculous price of $1.78 with free shipping so this is what I built....

 

MP3 Player

MP3 Player Lid

MP3 Player Chassis