The Raspberry Pi line of devices are inexpensive, low-power, credit card-sized computers. But while there are USB ports for connecting a keyboard, mouse, gamepad, or other accessories, there are also a series of GPIO (General Purpose Input/Output) pins that allow you to connect hardware in other ways.
For instance, you can connect a HAT (Hardware Attached on Top) board to add motor controllers, GPS, a display, orother features.
Now the folks atPi 2 Designhas launched a Kickstarter campaign for one of the most ridiculous/awesome-looking HATs I’ve seen. It’s called the 503HTA Hybrid Tube Amp.