Foreword: A interesting breath of fresh air in the IEM world. A hybrid design that uses a dynamic driver, balanced armatures and a ceramic piezoelectric tweeter (a la Radius?). Frequency Response Something of a W-response going on here. Not a lot of midbass slam but a lot of subbass rumble. 10k spike is definitely present and brings quite a bit of definition to percussions. Not a lot of lower midrange presence which makes instruments sound a little thin. Impulse Very, very clean impulse response. Sharp initial peak, zeroes out real fast with barely any linger. Not sure if it correlates, but the CE-5 does evoke a very "clean" feel to its notes. CSD No coherency issues that pop up on CSD here. Hyla's implementation of three technologies seem to be working well. THD Pretty much expected, the twin BAs working the midrange introduces third order distortion to that particular frequency band. Just like most other hybrids, bass remains low in THD. No farty BA woofers. Impedance Reactivity I forgot to do this. Setting reminder. Additional Notes Main glaring issue with the CE-5 seem to be timbre. Vocals don't have enough weight and sounds rather sterile and lifeless at times. Harshness can be experienced with plucked and strummed instruments in particular, possibly due to the huge 2-5k emphasis? It's a clean sound, but not something that I'd want to listen to for hours. Very in-your-face and overpowering. Bass is something that I absolutely adore on this IEM. The midbass hits are fast and clear while the subbass have a feeling of "pushing air" that satisfies the raging basshead in me. For me at least, a solid 10/10. I want this bass in all my IEMs. Foamies do help in alleviating the thinness and intensity issues that I've experienced in silicone tips. However, they do smear the bass a little, which is a compromise that I don't really want to take.