I tried out PiccoloNamek's EQ thread for removing resonant spikes and humps because I had always been disturbed by a painful shouty effect with my PL30's that I couldn't get rid of by trial and error EQing.
Not only is the painful shout gone but it really opens up the music. When comparing the before it sounds like the musicians are playing in a box. I very much recommend this method.
I haven't gone all the way with his guide (using pink noise to tune the width of affected frequencies ('Q' setting in rockbox) but I did find the hump's central point at 750Hz and EQ-ed down to -8db with a Q of 7 to be conservative. Previously I had tried 800Hz (trial and error) and it didn't do the job so finding the central point of the peak is important.
Do tell if you find this works for you also. Comparing the before and after is a revelation.