HiFiMan RE800 (and the effect of covering the tiny front vent)

Open vent versus closed vent (red line) illustrated. However, unless you have got really small ear canals and are using tiny ear tips that cover the vents, chances are low that the sub-bass will be this strong. For most ears and people, something much closer to the yellow line will be the likelier sound signature they will experience.

Versus HiFiMan RE2000:

Versus Etymotic ER-4S:

Versus Sennheiser IE 800: