Now this I could not believe when I heard it; Power spikes can destroy sound cards in PCs. Let's look logically at this statement.
Firstly, the rest of the PC is untouched and it is only the sound card that has suffered damage. This means the spike found its way through the power supply, bypassed all the other on-board address selection and CPU buffer ICs, all the other peripheral cards (printer, com ports, LAN, etc.) and sought out the sound card to finally weild its damaging energy in.
Ok, let's have a look at a possible alternative scenario. If a PC user complains to the local electricity company about the damage, the company may weigh up the costs of refuting such a claim against "paying for the problem to go away" - and the cheaper option may well be to help fund the complainant to upgrade from a 14 bit to 16 bit sound card. Wonder how the complainant would feel if they were conned out of £50 or so.
Ok, I agree, that was a bit cynical (funny how 'cynical' is so often used for 'truth') but in truth when there is nothing else damaged within the PC then the chance of the damage being a spike up the mains is about as remote as Mars colliding with Earth.
What I suspect is often not asked is "what was the sound card plugged in to?". I suspect that if the installation is inspected (this is assuming that it is not a con act to get the latest card) what was wired into the card is probably where any form of "spike" may come from. By this I mean damaging currents such as ground loops and the like.
One of these days the electricity companies will learn to start asking "Have you wired the PC to the manufacturers guidelines, and if you could have this verified by an independent consultant we will gladly take the case further". Now, such IT consultants do not come cheap and the problem may well go away in the first phone call!