Foreword: Advanced AcousticWerkes (stylized as AAW) is a branch of the Singaporean company "Null Audio" that specializes in IEM cables. AAW themselves specializes in hybrid technology (BA + DD) and have more than proven their worth in the field with the release of the W900. Frequency Response Impulse CSD THD Analysis: Slightly downward sloping response. Due to the use of a dynamic driver as a woofer, the perceived bass response is actually higher than what is represented on the graph, a sentiment that many would share. CSD plots show the appeal of dynamic drivers as woofer: slightly longer low-end decay. Subjectively, it translates to a certain "naturalness" that BA woofers can't really replicate. 1k ringing on CSD (left channel) is repeatable. Not sure what's going on there. THD measurements also show remarkably low distortion in the bass regions, a range that BA woofers would typically show high amounts of THD. It may explain the "texture" that the W900 can generate. Overall, a laid-back sounding IEM with exceptional bass performance. A fine example of what hybrids can do.