I'm stuck between the new HD-681 Evo and the HD-330. I think the HD-330 would be a better choice for me, as I listen to rock mostly, but I'm not certain if my laptop is able to drive them properly. I previously had the PortaPro's and I really loved the warm sound they produced. Right now this is what my HD-681 lacks and why I want to upgrade. So I know that the HD-330 needs an amp to be driven properly, but how bad/good is it without one?
From experience conducted with my own HD660 I'd say that without proper amplification they're going to be worse than an 681 unamped. Do you already own a HD-681? Then the evo really wouldn't make much sense as an upgrade.
As an upgrade it could be an alternative to first buy an amp to use with your 681, and when you can afford to upgrade the headphone, do so. But the 330 without an amp probably isn't going to be satisfying at all.
Also remember that some minor equalization could give you a (slightly) warmer sound out of your current headphones.
Edited by Simcon - 3/21/13 at 8:43am