Intro Rosie is an in-ear monitor made by JH Audio and Astell&Kern together. They said that Rosie is the universal and improved version of the JH Audio JH13 Pro Freqphase. JH13 Pro is one of the flagships of JH Audio since 2009. They had many years to think about what improvements they could do. Rosie didn't just pop out from nowhere. They made the universal and improved version of one of their custom flagships after 7 years. Also this should be noted, JH13 Pro Freqphase does not have a bass knob unlike Rosie.   Incredibly Necessary (!) Information...