It’s an interesting question. Peavey came up with some rather weird amp designs over the years. Some sound terrible, some turned out to be amazing. The Classic 30 is an oddball that’s become revered. His collaboration with Eddie Van Halen obviously relied on Eddie’s ear but it turned out an amp that became one of the cornerstones of modern metal. Lots of metal guys swear by the Bandit, a janky solid state amp. Shitty Rage practice amps are awful but lots of people love them anyway. And of course there’s the Decade, which everybody always thought sounded awful until it turned out that Josh Homme had been doing amazing things with one for, humorously, decades. So, yeah, Hartley doesn’t have a great ear in the way the Leo Fender and Randall Smith did. But his weird ear gave him an edge that nobody has had.