Can't talk about the quality but quantity wise the M50 have much more of a bass emphasis compared to the rest of the frequencies especially the midbass. I guess it might be true with the D5000 but even so the M50 have more of a midbass hump in comparsion to the rest of the frequencies.
Now to OP
You can hear the sub-bass quite easily. Just not in today's synthetic music where the midbass dominates so even if there is sub bass it is completely covered. Get a pair of D7000 and if you can hear a distant rumble then you are hitting the sub-bass. The thumps are all mid-bass.
I WAS reffering to the D5000... should have mentioned that