I need your advice – noise cancelling headphones

I need a pair of over ear (closed), noise cancelling headphones for use at work. I’d like some advice as to what to buy and where from.

They are for work so I want to spend as little as possible whilst getting something that doesn’t make dubstep sound like a fart in a biscuit tin.

My absolute upper limit on budget here is £100. Obviously, I’d like to spend less if possible.

Along with cutting out workplace noise, it’s also fairly important that my hankering for drill ‘n’ bass and speedcore doesn’t piss off my work colleagues.

So, the basic spec is as follows:

– Noise cancelling
– Closed back
– Flat frequency response
– £100 or less

I am ever thankful for your sage like advice.