300B or 845?

am new to tubes.
I have read the archives.
Can anyone explain the inherent differences between the sonic character of 300B and 845 tubes?
Given the amp cicuits are good and built to utilise the strengths of the tube - what differences are audible on 96db sensitivity speakers?
My music is all acoustic - and 90% is female vocal. I love the sound of a sweet intimate vocal - there are not that many - plus single instruments: guitar, viola, flute, fiddle. I like melody and rhythm. I don't cope with massed instruments be it orchestral or rock bands.
Any advice is deeply appreciated.