Only okay. I have $15.00 Monoprice earphones that produce about the same sound.
I agree about the heavy amp-dongle. I wear shirts with a pocket. I should be fine with this. I was more or less expecting this was a Bluetooth headset, but that's my error. The built-in microphones are disappointing in terms of frequency response and soundstage compared to my Bose Hearphones, ($400.00 list) which have different modes, any one of which is superior to the only mode here. One of my uses would be to help me understand speach against background noise, but the sound is just like an omnidirectional mic on each side of my head, so there's really no benefit. When I'm seated in settled listening position, I still have trouble with the rubber cables, which tangle and are microphonic. If the cables were replaceable, I'd add a star. I'd have no issue paying this much for something that did useful things in the amp, used the microphones to actual advantage, and didn't have the captive rubber cables. I'm not set up to measure the dB reduction caused by the passive noise reduction, but I can say that it's better than some of my collection of earphones, but not better than all of them, and I'm simply talking about phones that don't advertise sound abatement. I'm not being hostile here. I'm an engineer and an electronic musician, and I'm providing my perceptions, which, we all know, are really important to designers. I find myself going to the Monoprice mic-in-the-cord (which I never use) phones instead of these, or my vintage Sennheisers. The weight must be a factor.
Would not recommend to a friend.