Update: The Senns have grown on me a bit. I know there's debate about break-in being psychological or not, and I can't confirm it isn't (did I stop listening to the headphones and start listening to the music?), but the bass feels tighter, and the sound fuller. Given the right rock album they can even have some decent drive and aggression. I also find these 'pretty up' a poor-quality recording a lot more than the Grado, so that you have to look harder to notice the flaws.
I still don't think these were the right cans for me, though. My two least favorite things about them are the two Sennheiser 'signature' elements: The warmth peak around 150hz, and the rolled-off highs. But I can't say they're not a quality product.
