Gorgeous looking amp, well done Glenn.
Tyrell you are very lucky.
One of my headphone amps is also using transistor control for the heaters (2V to 10V, user adjustable), it's a good idea.
RWA also use D-Class in their designs and so do my B&O monitors.
I do agree with Glenn, no point for small powers.
Eric I can see the Muses inside Tyrell's amp.