Yes a good headset does help with playing, when you can hear someone running down the hall you can end up headshoting him when he walks around the corner
obvously you missed that. you might have been walking the corner, but that doesn't stop you from running down the hall. if you run by the vending machines then walk the corner you can still be heard at the vending machines. Basically what i'm trying to say is that he heard you b4 you walked the corner
+ the reason he might "prefire" is because of shadows, in the area by the vending machines you can plainly see the shadow sticking out, so i tend to prefire when walking by