I have been on this forum for some time now and after buying some iems both dynamic and balanced armature and also with 3-way configuration, there was always something missing. Now with new hybrid iems like K3003 and UM Merlin, I always thought they would give best of both worlds. After extensively going through the reviews and appreciation threads I wanted to have one of them, but it hurts the pocket a lot. So I was inspired to have my own. I wanted to go custom way because of its benefits. The drivers were purchased here , so one of the best dynamic driver IE8 and one of best sounding miniature BA TWFK. I have uploaded some pictures of the design and the process which are self explanatory. http://www.head-fi.org/gallery/album/view/id/661417/user_id/274175 Because I dont have any measuring instruments I had to rely on my ears and had to experiment a lot , so it took nearly a month to fine tune them and three iterations to get them right. Some of the problems were frequency overlapping between the two drivers/coherence issue with the hybrid BA-dynamic system, so had to match them , other problem was balance between the left and right as sound tube length and filter placement affect the sound greatly. So the crossover is done using both electronic passive components and sound dampers/filters. Now they are done I cant stop listening and smiling. I have been listening to lot of live albums with flac. Bass- Dynamic driver gives the bass feeling, so they actually rumble, so it adds lot of fun and pleasure to listen.With bass port you can actually tweak the bass. When bass port opening is very small the bass is deep and punchy , is quick with short decay times. If its opened more sub-bass comes up which also increases decay time.With this setting bass is tight and quick with good impact & with little rumble. If opened further it adds sub-bass rumble and also a bit mid bass but donot intrude into midrange which keeps it clean. Fully opening the port gives full-bodied bass rumble, and more mid- and upper bass, which can also cause slight coherence issue with two different drivers. Midrange is divided into two- low midrange which is warm and lush. higher midrange is detailed with good instrument separation. The midrange is not recessed in anyway which I have found in some of bass heavy dynamic iem. Depending on bass port setting I find the mid range slightly forward. Highs are well extended and crisp, TWFK is best driver for highs , same one used by the Audio-Technica CK10, Ultimate Ears 700, Fischer Audio DBA-02 You seem to have a 3d sound stage or the effect because of layering. They are easy to drive, but scale quiet well with an amp. Take above impression with pinch of salt. With more hybrids poping up in the market , they will become affordable and should be accessible to all . More people can enjoy and appreciate them.