I had a strong feeling there was going to be a tale to this. Even when they get to look at it, parts availability is likely to be an issue.
How old is this receiver now, and what is the warranty?
I seem to remember that your speakers are Klipsch La Scala. I think you had posted that they are not original but have been modified in some way. Have the crossover been modified and are the drivers original? If not then the impedance and phase angle curves should be measured. If these are not original, it might have contributed to the receiver failure. It does not take much to blow up the current receiver offerings. Since we live close I can easily do those measurements.