No... just... no. Any cans with a good sound-stage and open, more natural sound (like close to natural in this case) are not gonna seal properly. This is an ever-going concern. The best of headphones... the BEST of them, are always leaky. They will not seal you from the outside, neither will the isolate the outside from you. So it goes both ways. You wont get the desired isolation (some noise from the outside will get into your experience) and your music will certainly leak causing discomfort around you.
It's a trade-off, and simply not possible to achieve both. Technical hazard. You can't have both.
I understand this. I have totally open AD700's right now and I can hear what's going on in them from 2 rooms away in my house. A LITTLE leakage is ok, somebody in the immediate cube could deal with a faint bit of music, but I just don't want to disturb others at normal listening dB.
These are semi-closed/semi-open and they will leak a small amount of sound. Usually acceptable in most offices unless it's a near silent one like yours.
It's hit or miss here. Usually in the early morning it's dead silent. Once the day goes on, especially during and after lunch there's some background noise. I'd just like to have as much seal a possible while still getting a good experience. FWIW, I listened to some Sony MDR-1A's yesterday and was pretty impressed. Isolation seemed pretty good, I couldn't hear any customers or background noise from the showroom.