The Wrecking Ball is based on the Mesa/Boogie Dual Rectifier preamp's lead channel, substituing the 12AX7 tubes with 6N21B sub-miniature tubes. It sounds just like you would expect a Mesa-based tube preamp to sound like, and it will turn any amp into a face-melting metal machine.
The Wrecking Ball v3 sounds identical to v2.3, but the power supply has been redesigned to draw less current.
The Wrecking Ball runs off a standard 9V power supply, but because of the tube requires at least 1200 mA of current, so please be sure you have an appropriate power supply. I recommend the Visual Sound 1Spot (not affiliated).