[Critical50]

Im wanting to upgrade
Currently I have a pair of HD 558s, and Audio Technicha M40s
What Im looking for:
Portability. So removable cables or a cable thats only about 3 feet long is a must, but removable is preferred.
Balanced sound.
Not needing an amp, since I'll be mainly using it with my phone.
Im open to open back or closed back.

 

[NA Blur]

Take a look at the Noontec Zoro II HD and Zoro II Wireless. These are excellent sounding headphones and you can check out Tyll Hertsens' review here.
 
The measurements are included in his review at the end.
 
I own both the Zoro II HD and Zoro II Wireless and both have similar sound signatures in that they are up-front, accurate, and have excellently controlled bass.
 
These are both on-ear headphones so if that is an issue look elsewhere, but I find them very comfortable. The fold up nicely and they are sealed so no worries about sound leaking if you want to listen in a more public area.
 
They have a detachable cable and the Zoro II Wireless sounds crazy good for a Bluetooth headphone.