Cheers Rod,
It's actually working again like you said - took probably 2 weeks. However I did remove and checked nearly every fuse on the entire car prior to it restarting. - it didn't work straight away but a few days later! very weird...
The Lexus guys on the NSW Central Coast had never experienced it.
I saw the Amp's on ebay too, and I was in touch with some guys in QLD who said about $1000 to repair it, but I had to pull it out and post it.
If anyone stumbles on this thread and wants to change the Levinson Amp, I found out that it is located above the drivers side rear wheel but looks like you have to rip out half the backend of the car interior to get to the amp. A long weekend i'd say.
Mark