Usually those HTIB systems are made to go specifically with the accompanying speakers. Do the speakers have special connectors on them or just bare wire?
What is the impedence (in ohms) for the speakers? Hopefully it will say it on the back. Usually 3, 4, 6 or 8 ohms. If not, what is the model number of your system? Maybe we can look it up to find out the specs.
This is one of drawbacks of all in one HTIB systems. If something breaks you may have to replace the whole setup.