I have a NAD 317 amp that has just lost the high-end on the right channel. The volume is about 1/2 that of the left, is muddy and bassy. I troubleshot the speaker connection and the problem appears in the other speaker. Any ideas on further troubleshooting to narrow down the problem?
Swap the speaker wires (left to right and right to left) if the problem remains with the right speaker it is not the amp. If this proves true then check to see if your speakers have fused tweeters, you may have a blown fuse, the other option is a blown tweeter.