Using DPA 4061s (love the size) but the bass is saturating the signal.
You can't EQ it in post? I can think of a lot of reasons to use cards, but "I'm getting too much bass" shouldn't be one of them.
While 'EQ in post' is generally sound advice (for what we do), there are still many good reasons to use a low-cut filter in the recording chain. In this particular case (406x mics + EDM), I would say a low-cut filter is definitely needed, otherwise you're going to compromise the headroom of all other frequencies and end-up with recording that isn't listenable without post-processing.
I would say that the natural low-frequency roll-off of cardioids is a huge benefit over omnis for recording loud rock / edm / etc, in addition to being directional, but YMMV.
I have tried a bass rolloff filter 6db/octave starting at 120 Hz. This ruins the bass though.
6 dB at 120 Hz is criminal. Of course it sounds bad. I can only assume you are using a certain vendor's product that popularized this value almost 20 years ago. It was a half-way decent choice for Panasonic WM 60/61 capsules, but not at all appropriate for 406x microphones. I would recommend something like 80 Hz.
What recorder and input are you using? Depending on your recorder's input impedance, the roll-off value might not be 120 Hz at all. It needs to be calculated for each specific device and input impedance.