Didn't like the Z5, LOVED it! Used my iPhone 6 with it cause I was getting ready to pack up the booth. If I had more time I would have used the AK120II in my backpack. I was blown away by how amazing the Z5 sounded. The resolution was beyond anything I heard without any hint of sibilance. Low frequencies are well defined, not boomy or muddy at all listening to electric guitar. Sony could charge $1499 for the Z5 and I would still buy it. At $699, it's a no brainer! My comment about isolation is not about noise isolation. It's in reference to having the same feeling as being in a anechoic chamber. You can hear your heart beat.