I have had a pair of Audio Technica MX 40s for over a year - they were purchased from a Seller on Ebay for 29.00 - minus the ear pads and cable so I was unable to really test them until those items arrived. A month later I had it together and found, to my dismay, that the right driver was not ping sound. Unfortunately the Seller disappeared although his or hers track record had been good up until then and so was unable to get a refund at the time - or at least some help. apparently a few others never even received the items they had paid for, they were all various AudioTechnica products that were being sold at very decent prices. Wonder what became of it all. I removed cover and tested the resistance which Indicated a possible short etc. and have been contemplating a replacement driver ( about 50.00 Cdn. ). Tonight decided to plug it into the Schiit Magni. 3 and of course no sound from that driver so I casually gave it a good couple of smacks with the palm of my hand just for the heck of it and the dang thing decided to work. So far so good. I wonder if the diaphragm was slightly stuck - the wiring appears fine where it is soldered although it does travel along the headband from the left side. Has anyone ever experienced something similar? Hoping it will now behave itself - perhaps the headphone amplifier helped compared to the Luxman L 215 I had initially tried - maybe a higher output gave it the necessary current it needed. If it continues to behave itself perhaps I can give them a good listen and see how the stack up against the HifiMan HE400i.