Hi! I've designed a custom audio amplifier for portables that works with both speakers and headphones. It's optimized to have great volume range on a GameCube or Wii. Note: I'm not selling these anymore, but you can PM me for information if you want to build your own. Here is the board. Its dimensions are 24mm X 21mm X 1.6mm. Speaker output power is approximately 2W. Headphone output power is approximately 150 mW. Input voltage can be anything from 3v to 5v DC. Volume is controlled via normally-open buttons on the DN (down) and UP pads. The buttons should have a connection to GND. Headphones and Speakers The speakers I've selected are rectangular with dimensions 15mm X 11mm X 3.5mm. These speakers perform the best out of any speakers I have tested, and their size is optimal for small portables. I cannot guarantee the best performance if other speakers are used. Note: The rims of the speakers need to be touching a flat surface of a case/enclosure for the full sound to be heard. They should be seated tightly to avoid buzzing. The headphone jack I've selected has one normally-closed sense pin. Other jacks may be used as long as they have a normally-closed sense pin on any of the 3 input pins. Speakers are automatically turned off when headphone output is activated. The amplifier will output to headphones by default if you leave the HPS pad open. Here is the pin-out for the included headphone jack.