The trick here is finding a power supply that can supply the necessary amperage to power the amplifier. Now if you have a high amperage amplifier, then a computer power supply won't cut it, you'll likely need an expensive bench power supply . The other option is to keep the gains on the amplifier down so it draws less. A lower amp fuse would also be a good idea to avoid overloading the power supply. Then you could use a computer power supply. Again first thing is first, you need to find out how many amps(max) your amplifier draws. To get a rough Idea, you could check the fuse for your amplifier. If your power supply can supply that amount of amps, then you're good to go.