For what you're describing I can vouch for the 770s.  My husband has a pair and they definitely make my head rattle while blocking out everything around me - which is the reason I don't use them often.  Get paranoid not having any outside input at all.

I have a pair of 2005 880s that I enjoyed pretty well but no longer use.  However, they sound airy, for lack of a better word - huge soundstage.  I've since switched to a pair of HD580s that I got for about 180$ used, so they're within your budget.  Amped properly they have more than enough bass...

I used to use (and still have) a pair of HD465's.  I can wholeheartedly say that they were always very comfortable and sounded quite good for the price if you like the Senn sound.  That said, I don't have experience with your other options so I can only speak from limited experience.  I think I...

When I was using my 880s I ran my gain at 5, but I had the 250 ohm version.  Also, the gain switches are on the bottom, visible through cutout holes in the case, though it depends a little on which version you have - some have actual switches like mine, but I recall reading that they changed...