Are you referring to noise isolation (sound blocked by the cup over the ears) or active noise cancelling (external sound canceled by equal/opposite sound produced by the speaker)?
If you're talking about noise cancelling, this will severely limit the general sound quality, even with high-end headsets. Because the speaker is working to cancel the external sound at the same time it is trying to produce music/etc it simply can't do both effectively. I don't recommend turning on noise cancelling if you're needing to pick out detailed game sounds like you do in CSGO.
Good noise isolation, on the other hand, is the better option when it comes to gaming.