That’s just an aesthetic take on a what reviewers say is a great sounding amp. It’s a Gallium nitride power FET device that only the maker has access to, since he designed it. All other GaN devices are for radar and if used for audio, are modified or backward engineered. It replaces silicon devices as it’s way faster.
No, he designed the circuit, not the GaN FET used in it. He had some involvement when he was in the semiconductor industry, but it was not designed for his amplifier. It appears to be obsolete as well as he bough the remaining inventory and is changing to a different FET for newer designs. Your comment about all GaN are designed for radar is simply not true. Switching devices in power conversion (which is what a Class-D amplifier is), is a primary market for GaN and there are numerous devices designed specifically for this from a growing number of vendors. They are not even very expensive any more with low quantity orders under $2.00, and volume much less.
The switching FET is just one aspect of Class-D as well.
While Class-D is efficient, there is still heat generated. Putting it inside glass is going to maximize the temperature swing from turn-on till it reaches operating temperature. If you like to keep your amplifiers off, till used, it may not be ideal for consistent performance.
Marketing? .... Definitely, but the upgrade path is interesting and this method ensures the unit does not have to be opened. I wonder if those contacts are audiophile grade? $20-100 speaker binding post, $0.25 cent tube socket contact ..hmmmm.
