My three main areas of concern are; 1- It has to have a USB in 2- It needs to have a sub out as I'm planning to incorporate one to my system. 3- Perhaps most important of all is sound quality. My budget is about  $300, maybe a little more. Thanks in advance for the suggestions.

Looking to replace the stock earphones that came with my iPhone 6+. I currently own a pair of Sony V6's and Shure 440's that I use at home and I'm looking for something that sounds that good but portable. I would like some bass and clarity. No more that $60 maybe a little more, any ideas?  ...