No sound device (input or output) after surge through speaker

I had my laptop plugged in via a jack to a large speaker, when I plugged the speaker in to the wall (via and extension plug) everything immediately cut out, the speaker powered off and the macbook turned off and immediately restarted. Now I have no sound on my macbook and when I open up sound preferences there isn't a output or an input visible. I tried resetting PRAM and SMC but nothing's worked I assume the electrical surge has caused some hardware damage, does anyone have an idea what exactly it may have done? Could I just replace the soundcard and hope for the best? At the moment I'm using a very cheap external usb sound card which is working fine.