From his mouth to my ears.
He started working with them in the mid 80s.
The 1st amps he built for them were called ARD because they sounded "Ard!" (as in hard when said by an Aussie!)
You can see pics of those amps on the Wizard website.
Rick did TONS of R&D on transformers because the "aussie guys" would complain that their plexis started the night out sounding great and would finish up sound like mush at the end of the night. Rick explained that the trannies were so hot with heat saturation that it couldn't be helped so he started R&D on his amps and came up with a great combo including trannies that won't get hot even if left on for a week. In fact, that is one of my favorite things that I do when demoing the Wizards at the amp shows and that is to have people stick their hands through the cutout side handles and touch the transformers and feel how cold they are!