rrreaits not what i would call lack of low end, as much as detailed but not brain wrattling.
in most cases you endup trading detail for impact(just my exp)
now, if you wana boost it a bit, i have tested with my DIY cmoy, fiio E3 and E5...the E3 has the best bass, and does add to impact without making them sound any less detailed(to me anyway) the e5's bass boost isnt as good/powerful as the e3's but helps....i would say an e6 or better would do the job of adding some bass..
also these sound AMAZING with my cowon d2+ mach3 bass maxed out....
they also sound amazing with my
samsung r1
cowon x9
sandisk sansa clip zip(Rockboxed)
ipod classic 240gb(rockboxed)
Samsung Galaxy Note3(snapdragon version)
and a few other devices i have...i will say, if you have a bad source or use low bitrate mp3 files, these will not be your friend, they like anything by Etymotic will point out the flaws rather then smooth them over.