Strange crackly distortion but can't isolate the cause. Please Help.

I recently noticed that I was getting some edginess to the treble on my sound system. A kind of lispy "crackle" distortion occurring at the peak of dialogue that was appearing on audio coming from both my dvd player and cable box.


At first I thought my center channel was blown but I got the same effect when I hooked up a different speaker. The same effect is heard when I run the receiver in stereo mode instead of 5.1 . I then tried replacing the digital coax as well as the speaker cable with no change. Finally I decided that my Onkyo 502 receiver needed to be replaced entirely so I hooked up a brand new Harman Kardon 135. Even though the sound was improved due to the receiver being much better quality, the crackle remains!!


I dont understand what else could cause this problem. I have tired every logical solution I can think of, including the replacement of the entire unit. Has anyone ever had a problem like this?


Thanks.


Receiver is Onkyo 502 paired with Athena micras.