Well, after giving these a good week of listening......
They just aren't cutting the mustard for me. After owning a pair of Equation Audio RP-22x cans, these just don't have the impact and bang in the low end that I crave. The setups I listen to these with are in my sig. The main use is for determining which songs have enough bass to sound good in my car, so I need cans that can mimic the bang of the system in my car and these cans just can't. It's very easy to make them bottom out and the bass doesn't rattle my brain. I could see myself using these for my portable setup as they are a very balanced sounding can that, in spite of my observations here, do have pretty good bass but when I listen on my PC I need my wig pushed back.
Considering some Audio Technica ATH-PRO700 MKII's, think that'll do the trick?
Yes, these don't have tons of bass. I'm surprised you even got them, because I don't think anyone has said they do..wait except for Koss I think on the box they claim "Extreme bass response".
If you want to have the bass knock your socks off (or your wig) you can try the DT-770 Pro 80. These days not even the M50 seems to satisfy some people. The DT-770 Pro 80 is the one bass heavy headphone that I actually think is quite good. I even prefer it to the DT-990 Pro, which seemed to have even more recessed mids.
So, yeah IMO they have slightly, more like VERY slightly above neutral bass.