To answer in reverse order, I need to have the bass and gain set high enough to get a decent sound (valve preamp) to DI into the PA so turning it down isn't practical.
This means I have to use the volume to control levels.
For rehearsals, I have the amp set louder as I don't go through the PA.
Basically combining a 500W rms amp with a 102dB cab is very loud, so the practical minimum volume isn't to quiet. I can't get it quiet enough for use at home without using the 10dB pad and rolling back the gain, which is not much help.
On reflection, this pub was quite small and it didn't help we had parallel walls about 10 feet apart behind and in front of the left-hand PA speaker. I had a big resonance at A/Bb and that's pretty much exactly the wavelength fto fit between those walls. I think it was partly this resonance making the bass sound too loud.
Personally, the right solution would have been for me to not use the PA, or at just to have used one channel of the PA as the left-hand set wasn't doing much. In fact the whole way we were set up was pretty awful but what does a humble bass player know of such things?