As mentioned above 88db, 40hm not suitable for 300B SET, 845 is capable but you have to put up with great amount of heat, same with class A SS. I've had both, good for winter, for summer use need to look elsewhere. The other issue with these, heat is enemy of reliability, I experienced these reliability issues, when 845's let go you will know!
When choosing partnering amps and speakers, get the right tool for the job. SET's have to operate within certain limiting parameters, push them beyond their comfort zone and distortion rises exponentially. Transformers also critically important, undersized and cheap you'll get greatly increased distortion and roll of in lower bass and highs, 3rd order harmonic distortion levels also not great with these. Power tubes chosen also critical, quality tubes will provide lower levels of 3rd order harmonic distortion relative to 2nd order, also provide greater power output at lower level of distortion. And all this for naught if speakers chosen not compatible with these low power amps, think high sensitivity and benign impedance curves.
As for expectation bias, I've built amps and modified many components, there have been regressive, lateral and progressive moves. While one can fool themselves in the short term, long term listening will tell the truth if one has quality references for sound quality.