I highly doubt the opus is what caused the problem. If a wire melted, whatever was at the end of that wire was drawing too much current. The opus regulated voltage. It provides up to a a given amount of current. It cannot force current down the wire's throat though.
Wires fried, things smoked because you didn't fuse what you should have. A wire shorted, and there was no fuse to blow, so your power supply blew. When you're told to fuse things, no one is joking. It's 100% necessary or else things like this can happen. You're luck this time, but next time it could have been your car or even your life.[/scolding]
That said, what probably saved you is the fact that the opus has a built in fuse. However it probably took way too long to burn up because it was rated higher than the wire going from the PSU to the screen. The wire from the PSU to the screen needs a fuse.
There's a good chance that your opus supply is not fried. Find its built in fuse and see if it is just blown. Hopefully that's the only problem and you'll be fixed up without spending more than a few dollars on the fuse.
Also, what voltage does the external drive require. If 5 volts, you can likely just tap the 5 volt rail of the power supply.