Originally Posted by nc8000
Phones with a male trrs will in most cases work as plain headphones with absolutely no problem from sources with a female trs
Originally Posted by skamp
Produce a stereo audio file with some content in only the left channel, nothing in the right channel. Play it back with a male TRRS / female TRS configuration and put only the right cup of your headphones on your right ear. You'll hear the signal that's in the left channel, when you should be hearing nothing.
Whether you can use a male TRRS plug in a female TRS socket depends where the sleeve contact is on the socket. Some sockets have the sleeve contact positioned over R2 of the TRRS plug, some have it positioned over the S of the TRRS plug. Some bridge the R2 and S.
To be compatible with iPhone-type TRRS plugs (also used by Nokia and most Android phones), the contact has to be over R2. Some older Android phones have the R2 and S wiring reversed, and so their pack-in earphones will have R2 and S reversed as well.
I haven't found a TRS socket yet with an S contact that didn't line up with R2 on a TRRS plug, but I know they're out there. The easiest way to deal with it is to get a 3.5mm F->M extension cord; as long as the socket in the extension cord works, you can use that to plug into the problem device.
The T (left +) and R1 (right +) contacts are exactly the same on both TRS and TRRS connectors. If the contacts on the socket don't line up with them, you have some entirely unrelated problem.