How do I minimize outside noise while still listening to music?

[veggiop]

My main question is what are the most effective noise-cancelling headphones that are as loud or louder than the Senheiser PXC-250?


I'm currently a grad student and I live in a relatively loud environment. I ususally study to music, but can't do it when there are other sounds around me (aside the music itself)
What I started doing is wearing earplugs (Mack's Pillowsoft) that reduce noise significantly, and then wear my Senheiser PXC-250 noise canceling headphones over the earplugs.
It works pretty well, but I think I've overused the PXC-250 (the noise cancellation basically stopped working and the sound itself is getting spotty)
I'm looking to get new noise-cancelling headphones to study with (over the earplugs)


Sound quality isn't that important (because the earplugs muffle the sound anyway), but noise-cancellation and volume are important.
On the senheiser website it says the Sound Pressure Level (SPL) for the PXC-250 is 112 db. Not sure if that's a direct reflection of the volume, but i figure it has to do with it.

I'd prefer (but don't require) Closed , Circumaural (and blue-tooth) headphones, and price really isn't an issue.

Any suggestions?