It seems to me a lot here are bored with their speakers - thus enjoying the fun of the "tweaks" - I did same before and it is really fun.
From wharf 9.6, and here, the ideal target are the tweeters - so lots of peddled hyped caps flew in the air - and so thus with money, time, efforts, and failed expectations.
I oftentimes wonder why so many hobbyist frowns on tone controls and/or equalizers - which are readily available to correct response anomaly in a speaker (if they know the anomaly, though my guts tell me its this "unknown" in our usual stuff) - or to cusomize one taste of sound as in ones coffee.
These are merry-go-round of no substantial (and sometimes surprising) results - unknowingly altering frequency cross-overs that may definitely result to some sonic change - but if for the better is all but a guess or subjective assessment of the diyer.
Speakers are never flat - before we have the curves of speakers in the specs, now its a goner - simply because taste for speakers will largely depend on the subjectivity of the owner.
Simple addition of high sensitivity tweeters could have done the trick, and attenuate to balance to ones taste. Equalizers in conjunction with analyzers are often employed by those who understood their issues - but maybe used to tailorfit our ears.
But then - go for the fun. This is not the type that the end justifies the means. If you meant otherwise, do the simpler things. Simple problem deserves simple tweaks!