I have the same headphones and coincidentally also tested with Take The Power Back.
The bass is good on the Pro 900 and for really sub bass stuff it's great (like James Blake Limit To Your Love). But a lot of RATM songs, I find that the HD25 kick much harder than the 900 (ex in Take The Power Back, the part right after "bring that sh_t in")
For bass quality and quantity - Pro 900. For bass impact and "thumpness", I haven't heard anything that's better than HD25.
Agreed, the HD25 has more impact, but has nowhere near the sub bass of the Pro 900.