I was misguided with HV=800V and bias ~120V, I read 60mA from the curves...haha. Well, with 800V/100mA/-109V you certainly can get 30W in A class with Raa=10k. And in my view, GM70 is a great alternative, quad can be found for $105 ("Anthony Welsh"), and even the sockets can be found (www.roehretechnik.de) for about 10 Euros each, not too bad. No experience either :-(.