Stereo Headset "circuit turbo" to increase the dynamic range. For me, the best I've ever had, even compared to other more recent productions and tell upscale (seinheiser, koss, bose, and others). I bought at the end of year 80.600 francs I think. There are for sale on e-bay (rarely) and say prohibitive prices (I've seen $ 250). Ear Headphones very lightweight (the in-ear did not yet exist) and when the door, we do not feel it. We can keep hours without being general. As for the bass and treble are transfigured. When I put it on, I find myself feeling the disco without the need to mount a strong, even with flanged devices in Db. Being an insomniac, I listen to music at night bcp on a mp3 with sound 1 and sound quality remains impressive. I found a ref. sony which uses turbo, this is an in-ear ref. MDR-NC13. Try it. Another ref, the MDR-A10. This is the same version pliable. In summary, if you have the opportunity to have one, go for it!