Apologies if this idea is completely stupid and a no-go, but could there be any SNR benefit to putting the Beepre attenuators after amplification (after the 300Bs), instead of before? I ask only out of curiousity. I'm not trying to troubleshoot anything (my former hum problem has disappeared on its own and the Beepre rebuild prototype with the giant copper foil caps sounds superb).
MTIA, Derek