Replacing my Ultrasone 550's, any alternatives you'd recommend? ($100-180 closed over-the-ear)

[billybombill]

Got my Ultrasone Pro 550's last week, and while I love the sound the left side is louder that the right (I've tried different sources/cables and checked the balance on my sources and it's definitely the headphones). As such I am planning to return them and get a refund (can't exchange as I bought the last one in stock from the seller I got them from). Personally I like the sound of the 550's and would keep them if it were not for the driver imbalance. I am thinking about repurchasing them but I would be looking at around $180, compared to the $140 I paid for them. My only complaint so far would be that Ultrasone seems a bit hard to reach (repairs/warranty must be done through the seller, no US-based support) and that the included coiled cable required me to use a 1/4 -> 3.5mm adapter. Are there any headphones you would recommend in the $100-$180 price range? Looking for closed over-the-ear, noise isolation is a plus, and (If you've tried the 550's or related model before) a similar sound as the 550's. I've seen the ATH-M50's recommended a lot but they also seem a bit over-hyped, and a friend of mine who has them says they weren't really worth the price.
 
TL;DR - Looking for upgrade from Ultrasone 550
* $100 - $180 (preferably under 150)
* Closed back, over-the-ear
* Case and/or detachable cable a bonus
* Comparable sound to 550's if possible
* Comfortable (5-9 hours a day, if not more)