Got hold of some black Fiio Ex1, which are successors of the Dunu Titan 1, claiming to improve on those while pertaining the sound that many have reviewed rather positively. Stock sound impressions mirrored what others have said about these: good bass, recessed lower mids, elevated highs. The highs are not a problem for me, but they are a little too hot from 3 to 5kHz, especially with that preceding recess in the lower mids. Stock measurements with Complies, compensated. Using my DIY measurement rig, so do take those measurements with a grain of salt. But they are good enough for comparisons between stock sound and mods: These sounded really good when not cranked up. But the elevated region above 3kHz bothered me when listening at higher volumes. So I tried some mods, the aim being to bring the lower mids up a bit to reach a better balance. Mod measurements: Red is stock, blue is with bass vent (tiny hole at the back of the shell, directly next to where the cable enters the shell) completely closed and yellow is what I ended up with: partial blocking of the bass vent and closing 11 of the 12 front vents, so all except for one hole! Closing all 12 holes turns these into bass monsters! I won't say these sound perfect now, when listening I feel that there is still too much energy from 3 to 5kHz for my tastes, but the lower mids have been brought up and balance has been improved. Final version: Build quality is excellent,these are made of aluminum and the finish is top notch. I used a colourful tape to show the front vent mod.