"very bass heavy" depends on what headphones you were coming from previously and what music you listen to primarily, honestly to me, coming from xb500 and listening to mostly hip hop and edm, these things stock are bass light to me, the bass is punchy and tight, the mids and highs are detailed and i personally find all 3 are separate and distinct, its only when you eq and use certain bass oriented dsp's that the "heavy bass" people on here brag about comes to the forefront, and you get that head rattling slam you hear everyone talk about, its at this point where you might find some bass bleeding into other frequencies but unless you're overly critical i really wouldnt complain too much about it
these arent meant for listening to classical or acoustic music on anyway so if you feed it bass intensive music you really shouldnt notice anyway, if you plan on using them for rock they're ok i guess, i think the bass could stand to be a little quicker for my taste in that genre as it doesnt decay fast enough, but thats what grados are for anyway so "meh" lol
if you like your music to be neutral dont get these, also if you're worried about bass being too overpowering just dont eq them and play them flat stock and you should be okay for most genre's if that's your preference