Are there any advantages/disadvantages of using the 240VAC power transformer vs 140VAC mains? Which one is the most preferred option?

  I don't have a budget, but I would prefer not to spend more than $1000 for a headphone if possible. I don't have crack, but I plan to order one soon because I heard it pairs and sounds really well with the Sennheiser headphones. If I can get the HD 700 between $500-600 USD, should I go with...

Thank you for the welcome roguegeek!   The type of music I listen to is mostly soundtrack from movie/video game scores. Sometimes classical, rock and pop, etc. I do like good bass and warm, clear sound. The HD 700 seems like a good choice for my needs, but if either the HD 6xx and HD 800 are...

In regards to sound quality, is the HD 700 with bottlehead crack a good pairing or am I better off with the HD 600/650 with bottlehead crack?