It's no competition there.
The HD650 wins the IE80 flat out.
But that said, the IE80 is the top of the line IEM offering by sennheiser.
Both sounds sonically the same in terms of signature
Except that HD650 has tighter bass. And has more definition all around.
I'm running both my IE80 and HD650 on twags.
Second that. The only area that the IE80 rules is portability. I had a lot fun with it on a 2 weeks camping trip this summer, where the HD650 plus amp plus 12 volt battery pack was simply no option. If you cannot compare, the IE80 really grows and lets you enjoy the music wherever you are...... imagine listening to your favorite tunes while watching the sun sink into the Mediterranean Sea.... It was simply great.
Edited by pietcux - 11/6/12 at 3:03pm