There seem to be a slight problem with the E17's headphone jack. The channels seems to become unbalanced when used with big adaptors and other plugs. I assume it's caused by the stress from oversized plugs?
Here's a picture I found on the internet, showing the insides of an E17. Maybe a different way to reinforce the jack can be used?
PS: The metal body on the E17 feels great, and I like how clean it sounds with my IEMs