I am not very familiar with the pro speakers. Are they some kind of passive speakers (without any amp)? If there is an amp with an external power plug in there (what I believe), you will have a cable that is 2x cinch to 1x jack. Simply replace that one and see, if things work fine.
However, if your speakers are passive, you can chop off the faulty jack and connect a new one to it. Just make sure you isolate the connection-sites of the cables well or you will have a lot of noise in your sound. Good luck!