The adaptor only works when slightly out of the audio input. (When pushed in completely you get either no sound at all or a very strange version of what you expect to hear.) You therefore have to be very careful not to move your headphones or whatever they're plugged into - which certainly rules out using my headphones via this adaptor anywhere away from the serene, tranquil conditions of my humble home.
It'll do for now but will ultimately need replacing with something of an adequate quality i.e. with something that works as you'd expect it to.
My experience seems to be atypical, but in my opinion, look for a superior item on good old Amazon - or maybe even consider venturing to a real shop (as I will now be doing) - in order to get something that you know will definitely work.