The main selling point for X2 is the impedance of 32 ohms. It's uncommon to see open cans rated such low. This is not the best open cans in the range, honestly. You've got better alternatives like Shure SRH1840. I think the sound quality of X2 is almost matchable with my HD600 that too with...

As you said noise isolation is crucial for you, the headphones that excel at bass tends to offer such extreme isolation.   Here's the good-old thread http://www.head-fi.org/t/716711/the-hardest-hitting-headphones-are-the-extreme-bass-club     Go for bass headphones as they will offer more...

What about the bass guys? The earpads are not durable though without spares.

Bose SoundSport would be a good option. Even it is discussed at various threads of Head-Fi. Example here and here.    http://www.head-fi.org/products/bose-soundsport-in-ear-headphones-apple-devices-energy-green...

I recommend Shure SRH940 headphones they come at $250. These are true reference headphones and good for classical. It suppresses an ample of ambient noise, which is great for office nature. If you are for Beyers then go for DT660. These two headphones are great at sound isolation.   You can...

LCD 2 is great. But for some bass is bit lacking and as you said weight maybe an issue. I would also recommend you looking at ATH-A900x they also excel at bass. These are my closed-back cans suggestions.   Shure SRH 1540 and HD800 are my picks for open back headphones. These are often used by...

Earbuds or earphones I often use them interchangeably. My pick is Bose SoundSport Wireless, they seal sound well.

I would highly recommend you getting Bose SoundSport Wireless earbuds. It's really great and offers unmatched comfort for me. Sennheiser MX75 is also quite great.  If you are looking for full headphones, I would recommend you Sony MDR-V6 or Koss SportaPro on the lower range.   I would go for...