Peter, it's hard too figure out exactly what's the cause of the problem, but well-recorded CDs should certainly not be harsh on the equipment you have if it's in good operating condition. Checking with the 818 supplying the power alone is still a good suggestion.
One point to note on Audyssey is that the "Movie" setting is in fact the "Audyssey" curve, although the manual doesn't explain this(surprise), and rolls off the treble at about 2dB per octave above 4KHz. The Movie setting can also be used on music for particular discs which have the treble too hot. The regular "Music" Audyssey setting is the "Flat" setting with no treble roll-off.
