The Trio's connectivity is limited to a 3.5mm stereo input analog jack, and a 3.5mm headphone jack. Thanks to the amp's low/high gain toggle switch, Trio can drive in-ear and full-size headphones.

The triode vacuum tube might be nearly obsolete today, but it was a technology critical to making radio practical over 100 years ago. [Kathy] has put together a video that tells the story and expla… ...

Lee De Forest invented the audion, a vacuum tube device that could take a weak electrical signal and amplify it into a larger one. The audion helped AT&T set up coast-to-coast phone service, and ...