WS-420's aren't on back order as far as I know. They came off of backorder a month or so ago, but shouldn't be behind now.
Robby, you're problem isn't the same as Harolds. His doesn't work, and it sounds like yours still does. It could be that your's is clipping. I noticed with certain music my Rev10's will do the same, but I turn it down all the way, then back up to a "lower than before" level, and it's fine. It doesn't matter where the volume is because you're system is tuned by you, and not us. If the pre-amp comes in, then it's working properly.