The HD 6XX replaces the HD 650’s and is crafted with the modern audiophile in mind. The driver structure and sound signature haven’t changed a bit. You’ll get the same smooth, laid-back presentation. And, it has a balanced midrange and natural-sounding bass. The HD 650 is considered more refined and better damped than its predecessor, the HD 600, with less energy in the upper midrange (which some listeners may find less fatiguing) and an overall balance that’s a bit warmer and bassier. Its neutral response provides a pleasant listening experience with any musical genre from a range of sources.