Just a thought - one way I control the volume on the bass of my box is to play staccato (as if the keys are so hot I can't hold them down) if I want to quieten it, and hold them down longer if I need more volume. As I play mostly for Morris (he's a nice chap, y'know!), it's important that it doesn't sound 'mushy'.

Quite often smaller accordions are bass-heavy, which is odd when you consider they are intended for beginners!

My big box has five reeds per single note in the bass, with couplers allowing the deep bass to be de-selected, or all but the two highest to be de-selected. Very handy!