let it burn , play music for at least 50 hrs , 7-8hrs sessions at moderate volume ( dont use them , let it lie at a safe place , listen to it when ever you want to check the changes , they will open up , highs will drop , and people out there love this kind of spark at top and it is clearer sounding then ep-630 , this spark will go down but not much , and this is called better reproduction of sound , and about wh205 , it lacks extension at top end and is spark less . keep no doubt , es18 is a far better phone then ep630 or wh205 .
i was not aware of you sensitivity for highs , or i would have had you going for ep-630 or ep-600 , i like these creative phones have gifted my friends but its not for serious listening at all , they are muddy and veiled too .
" or " you can equalize it , bring the frequencies over 4.5k down , till you find them tolerable .
you can play with eqs , and find out the best one for you .