[Hampshire] [OT] CD device with mono audio out

Thought I would ask the knowledgable mailing list

I have to get a music playing device (prefably CD\DVD) of some form that has a
mono 3.5mm output socket so that I can hook it up to a phone system. The
device must also have continuous play and be able to play MP3's

Does anybody know of such a device and where I can get one, or how to convert
a 3.5mm stereo out to mono??

Thanks in advance

Tim