I note the Forked Tailed Dr's comment about the DC X-11 not cutting out the noise. It's the same for all of the "designer" ANR headsets - Bose, DC, whatever. If you ask the manufacturer what the passive attenuation is they say "we don't publish it". As I understand it the passive for the DC X-11 is 17dB which is not enough for anybody who respects their hearing. The ANR only deals with LF noise so you are left hearing all the HF noise and much of the non-regular LF.
I don't believe that any of the carbon fibre, phone interface, MP3 life supporting headsets give proper hearing protection.
On the other hand try a set of DC H10-56HXL - the quietest headset you will ever find without the ANR turned on and truly amazing with it turned on. It has 27dB of passive and another 22 or 23dB of ANR. And never mind the weight my very lightweight daughter wears a set for extended periods no worries.
If you want a phone or MP3 interface then get a Flightcell.
Look after your hearing.
MJH