If you know that it is only the tweeters that have blown—meaning both channels sound fine except for the lack of top end—chances are good that the amp is fine and not the cause of the tweeters blowing. To be extra cautious, you could try very cheap speakers on the amp.
Do you recall how loudly the speakers were being played at the time the blew? It generally takes pretty extreme conditions to blow a tweeter. If they went following a short but extreme burst of energy, like a loud blast when switching inputs, there is less of a chance of other parts also being damaged. If they were being played loudly for some time and went following sustained strain, other parts, such as crossover components should be inspected. If you can get to the insides of your speaker, inspect the crossover board (‘I’ve seen plastic inductor spools melted into a pool of plastic), disconnect the tweeters and check for continuity with an ohm meter. I hope it is just the tweeters that need replacement and that there are drop in parts that will work well enough.
