i thought i would be disappointed too with the bass output so i got a fiio e11 also... just to be "shure". but now i see that it doesnt even need an amp to sound great straight out of my ipod classic or macbook.
amped... its becomes an even greater headphone. then you got options of EQ'ing some more of the lows if you find it "lacking". its gonna take that and give you what you want. great great headphone overall. big upgrade from my srh440s.
and yes i agree with a lot of posts saying that source is very important.
enjoy. be ready for quite a surprise. :)