Impedance is the device’s electrical resistance to the current being pushed through it. The lower the impedance, the easier it is to get higher volume and requires less power.
A straight plug is better when the jack is on the top or bottom of your player.
3.has a tangle free cable
The cable is designed to minimize tangling.
With a detachable cable you can use alternative cables, and if the cable is pulled it will pop out instead of breaking.
An L-shaped plug is better if the jack is on the left or right side of the device, so that the cable isn't bent, and is less likely to break when the device is in your pocket.
6.Has an in-line control panel
There is a control panel on the cable, so you can easily operate the device without having to interact with it.