Generally the two dollar ones from chemists seemed to do just that. Thus I forked out ~150 bucks for some earplugs that brought down eveerything by ~25dB

I don't know why you would want to do this. Our ears are less sensitive to lower frequencies, meaning we hear lower frequencies at a higher SPL to have the same volume as higher frequencies at a lower SPL. Which to me seems to imply that we should be concerned about bass frequencies damaging our hearing, even though it's often the high end we percieve as "hurting".
However, I did find that my superduper earplugs did seem to reduce the high end more than the low end. However this could be due to the “equal loudness contours” or Fletcher-Munson curve. In other words, our perception of relative volume of frequencies when compared to one another against their SPL differs at varying levels.
Yikes, what were you asking again?
