Cassio was born and raised in Sao Paulo, Brazil. In 1985 when he was a young teenager, he and several friends founded the hard rock band known as Viper. Cassio Audi‘s founding partners and bandmates included Yves Passarell, Pit Passarell, Andre Machado, and Felipe Machado. Audi was not the only young founding member of the band. At the time of the founding, all of them were either 13 or 14 years old. The band played hard rock in the thrash metal, power metal, heavy metal, and alternative rock genres. Prior to becoming an established band, the group put out a demo in 1985 called The Killera Sword.
It was extremely well received. The shortly thereafter put out another very well received demo. The first official Viper album, Soldiers of Sunrise, was released in 1987. It included songs like “Signs of the Night,” “Knights of Destruction,” “Nightmares,” and “Soldiers of Sunrise.” The album became very popular worldwide, prominently featured in top hard rock magazines like Kerrang, Metal Forces, and Metal Hammer. This resulted in then selling more than 10,000 albums worldwide. In 1989 the band released a second album called Theatre of Fate and more
It was particularly noteworthy among critics for its brilliant mix of classical and metal sounds. During this time, It was so popular that it beat out on the charts the then hugely popular rock bands Van Halen and Nirvana. Audi himself was a huge influence of the Brazilian hard rock sound that came out of the 80s. Audi left the band that same year to pursue a career in finances.