I have posted this information in this section but I am sure there are many like myself who have to use headphones more often than not and my comments could be applied to many other sections. I must also say this is just my recent discovery but I am sure members may be well aware of this information already
The fitting of the 3.8 stereo jack plug in some cases to computers line and out connections and audio units are very neat but many peripherals such as amplifiers, expanders, mixing units etc still use the 1/4 inch jack plug that requires an adaptor to make the connections. The adaptors I find are the weak link causing the most common fault which is to pass mono signals only.
The reason is simple, inside the adaptor are two extended prongs of differing lengths which make contact with the respective area of the 3.8 prong from the side. If you have to keep changing the jack plug size to connect from one size to the other the 3.8 plug can soon become quite loose inside the 1/4 inch adaptor and instead of being held tight in the central position can " wobble" this imparts too much sideways pressure on at least one of the contact prongs in the adaptor and contact is lost as the prong does not always return to it's normal rest position .
But someone has come up with a simple idea to stop it " wobbling " make it a screw thread completion so you can make it a tight fit.
I bought a new set of Behringer headphones recently for £12.30 with these already fitted and what a difference it has made, I usually had to use new adaptors after a couple of weeks sometimes, now I do not appear to have the trouble.
The screwed adaptor is also available as retro fit pair of screwed together 3.8 and 1/4 inch jack plugs which you can fit to the cable of your existing set of headphones but the cost per item is about £6-£7 , it is a very fiddly job and when comparing the cost of a brand new headset and not having to struggle with soldering irons and purchase of no more adaptors in future it's a no brainer in my opinion, sorry I could not find how to post a photo but there are plenty of examples on ebay or amazon. Ken