It's not bad though, I still enjoy some Kanye West on the 12.0 the bass is still good.It is easier for a headphone to achieve lower bass than loud speaker, especially for in-ears/air tight. Diamond 12.0 is the smallest model that reach only 65-70 Hz. So, I'm not surprised that you switch to hifiman he400se headphones for those music genres. It would be a better comparison if you add a good subwoofer or compare it with Diamond 12.2.
Worried about using a subwoofer or 12.2 because I live in an apartment so don't want to disturb neighbours.