That's the thing. What's considered a high failure rate. The issue is not isolated to the LX. On other forums and sites like repair pal there are a lot of complaints. One site shows complaints as far back as 2001 vehicles.
I called United radio, who a lot of owners use to repair the amp and while they could not share how many repairs they got from Lexus owners grey did confirm that it is fairly often. This is sounding like a common issue to me. Even the dealer I took it to kinda confirmed that.