In article ,
says...

On 22:03 24 Nov 2016, MJC wrote:

In article ,
says...

I'm impressed. In some other groups I've been asking about a
one-piece stereo to mono headphone adapter. I want one with a
built-in switch but even though it's not available I don't
think I'll be doing that to fit one!

http://al.howardknight.net/msgid.cgi?ID=148001642200

If, as in link, it has a mono socket, what is the "mono/stereo"
switch going to do?

Mike.


It would allow stereo headphones to play mono in both channels
(rather than in just the left channel) from a mono socket.

You're going to need a stereo socket for that! (I had hoped you would
work that out for yourself with my prompting!)

Mike.