20 Hz subsonic 350 W RC low pass filter
Just throwing together some numbers:

Per passive RC filter stage, you get 6 dB roll-off per octave.

You need your transition to happen between 22 Hz and 30 Hz, that means you want some let's say 40 dB attenuation in ca half a decade. That demands, very roughly, a steepness of 80 dB per decade. So, a 13-stage passive filter.

So, we can simply rule that out practically.