 He is widely known for his keyboards, producing, engineering, mixing and remixing, and digital audio skills with Mötley Crüe, Metallica, Fuel, Methods of Mayhem, BT, Monster Magnet, Tommy Lee, Day of Fire, Powerman 5000, The Cult, Andrew WK, Spineshank, *NSYNC and many more.Humphrey has also co-authored and arranged songs with some of the artists he has worked with.According to Digidesign’s chief software programmer Mark Jeffery, Humphrey conceptualized and motivated him to write Beat Detective, Batch Crossfades and Sound Replacer for the Pro Tools audio workstation platform.