So I am looking for a method to do this.

Small Guitar Effects Unit Line Out/phones jack__________ Headphones

Mp3 Player Line Out/phones jack____________________/

I have a feeling some sort of mixer is needed for this, but I am hoping there is something more simple like a 2 1/8" male to 1 1/8" female cable.

Any ideas? Thanks

there are wires available for that.

you'll need a stereo female 1/8 "Y" adapter that has two 1/4" ins. you can just stick another adapter in your mp3 player (1/8 to 1/4) so you can use a mono guitar cable for that. it'll cause some panning, but not that bad.

there are plenty of other ways to do it, since it's just for your own use, doesn't have to be all that fancy. maybe just this idea will ring a bell.

Thanks Seb. I had so much trouble finding anything on the internet that I wasn't sure if they were around.

I ended up getting a mono one so my ps-04 is in one ear and my x5 in the other.