Originally Posted by Hifi Man
I'm not sure what this means. Sorry
Watch an unboxing video of the HD558s and you will understand.
The size of the headphone jack on your iPod is a 3.5mm female jack, only a 3.5mm male jack and be inserted into it and work. The end of the cable that comes with the HD558s has a 6.3mm male jack, which will not work with a 3.5mm female. But it comes with a rather bulky adapter that changes the end of the cable from the 6.3mm male to a 3.5mm male so it can be used with your iPod, but both the adapter and the normal end of the cable combined is almost 3 inches long, very bulky.
I would suggest getting this cable from Amazon, which is a 2.5mm male jack, that can work with the female end on the HD558s, and it ends in a 3.5mm male, which will go into your iPod. That way you dont have to deal with the 3 inches of termination and adapter to use the HD558s with your iPod.