Does your Wave not even start up anymore, or does it turn on and then refuses the make sound but otherwise seems to work okay? And did the amp short-circuit and die, or is it still (partially) working?
The only connection between the Wave and the amp was the output cables from the Wave, right? They may have been connected to the same power, but the power supply in the Wave has some filtering and that fuse, so I don't think the Wave was damaged via the power cable. Still possible of course.
Do you know what input the Wave was connected to? Was it a mic input that can provide phantom power? I can imagine the thing put phantom power on the jacks the Wave was connected to; I don't think the Wave would like that. It would like it even less if the voltage was even much higher than the 48 volts provided by phantom power.
The Nords have EMI filters (with surge protection) on the outputs. You can clearly see them in this image of my Nord Rack 3.
I've put a yellow box around one; there are 17 in the image. The thing directly to the right of the one singled out is a capacitor - it has Cxx next to it, while the EMI filters are shown as Fxx.
If you still had it (and had a multimeter), you could check if those EMI filters were still okay (= they conduct with very low resistance). Of course, if the Wave doesn't even start up anymore, there's little use.
If the Wave somehow got damaged via the outputs, a DI box might have prevented this. On the other hand, so should the EMI filters I think.
As Mr_-G- mentions, visual inspection of fuses doesn't alway work that well. The best way to check them would be with a multimeter; a 12V lightbulb, a 9V battery and 1-2 bits of electrical wire would also work.
I hope you get it fixed soon
