DJM 250 mk2 - master output to single speaker

Hi all, 

I am trying to connect my djm250 mk2 master output to a single speaker however in doing i am losing half the sound. 

there is no phono / stereo option

i was able to solve this on my previous djm600 by panning all sound to one side, however this is not an option on the 250mk2  

i don't believe a Y splitter for either RCA or XLR will work as not designed to merge sound but split (as name suggests!)

any suggestions would be greatly appreciated 

accept might need to buy an external DI or amp but not sure where to start

thanks in advance