Morning all

We seem to have some kind of plague ripping through all of our smartboard speakers, the amps appear to be going in them as turn the volume past a certain point results in the speaker dying. These are speakers fitted to SB680s...

Has anybody found success in using 'compatible' speakers, ie they fasten to the brackets of the SB but they aren't the same ridiculous cost? Or has anybody had success with repairing failed speakers?