I hadn't heard they ran the tubes hard, its possible. I'll have to check the schematic to see how much (quiescent) current they are running at. I know they run at fairly low voltage. The stage however isn't unity gain. Its an SRPP or mu follower, can't remember which, which means two sections are used in each channel, one for gain one for unity buffer. That is why there are two tubes.
I haven't rolled tubes in it yet.