Conversation so far:
What is JEM for Steve Vai?
Vai designed the Ibanez JEM guitar
What was unique about the Ibanez JEM guitar designed by Steve Vai?
a unique instrument that incorporated a series of groundbreaking designs that have since become staples in feature throughout the guitar industry

Question: What was different about its sound
Self-contained rewrite: What was different about the Ibanez JEM guitar's sound