Ive been happy with the Vox bass headphones. Short chord but it goes straight into the jack on your bass so it's not an issue.
I was surprised at the sound i got out of them and they really pickup fret buzz and clicks well so ive found them good for improving my technique through certain areas to reduce my aggression for example.
They have an input jack as well for an ipod or similar. Youd need a male to male jack for that.
All round id say for practicing without an amp Ive had no complaints.