I would start with swapping the interconnects...a lot easier than swapping preamps or getting your CJ repaired. See if it stays quiet. As discussed, i had a problem with my Oppo...and it appears to be that the RCA jacks are loose and there is crackling in the left tweeter as a result. In your case having both tweeters crackle means it is unlikely it is the RCA connection unless both are faulty.
Good luck...sounds like you are getting there.
Good luck...sounds like you are getting there.