If you've been afraid to test out tubes because things might explode all Mickey-Rourke-at-the-end-of-Spun style, check out the THD Bi-Valve 30 self-biasing head. It's the guitar amp equivalent to the world's safest meth lab. Still, you should exercise caution. Owen O'Malley demonstrates the Bi-Valve 30 while also demonstrating how to take precautionary measures against burning your hands and not blowing $#!+ up.