Hello,
absolutely I need to confirm the GaN Fet AGD uses for the Audion, Vivace, and Tempo (either in the AGDGaNTubeKT88MKii or in the new GaN power module for the Tempo) were optimized specifically for Class-D application hence for Audio.
The article of Rick Backer is therefore perfectly correct.
I cannot disclose the name nor the products of the 2 very large customers these chips were originally intended for (customers of International Rectifier), but I can confirm these were 100% audio applications. The current GaN-Fets available today from many suppliers are indeed designed and specified for Adapters and Battery charger (pc/tablet/phone) applications, and they have therefore different characteristics (very different) than the one we are using. To use them in Class-D is possible of course, but several additional layers of circuit design optimization are necessary.
Hope this closes the case about the truthfulness of what Rick Becker reported.