The classic Dennis Had-designed Cary 300B SETs, from back in the day, were capable of 9, 10, 11 watts; the one I owned drove my ProAc Response 2.5s to volumes I would never listen at. So the JA measurements of output of the WE did give me some pause. OTOH, I don't remember the reviewer reporting any problems.
New Western Electric 91E 300B Tube Integrated Amp REVIEW !