I wouldn't recommend orthos (HE-400) unamped.
Well, you're looking for details, sound stage, and comfort. If you don't have a small head or wear glasses, I think the AKG K550 would be great. You can find it for ~$200 new too if you buy from Europe (yes, 150 euro to buy it then ship to US from Spain); also there's one in trade forums for $190 if you want to help out another head-fi'er. Some may find the AKG K550 lacking in bass however; if you're used to a bottom-heavy sound, the AKG K550 will feel anemic. However, their wide, natural soundstage, low impedance (32 ohm) and high efficiency (114 dB/mW - WOW) makes it great for unamped use.
If you're looking for a boomy bass, look elsewhere though. You say you're looking for a detailed headphone that's fun but not analytical; usually analytical suggests detailed and neutral, but since you're looking for details and avoiding analytical, I'm guessing you want an exciting frequency response. Not sure if you're looking for bass heavy response, V curve, or emphasized highs. Perhaps you could clarify to get more personalized recommendations rather than whatever headphone someone else is enjoying at the moment, because it may not be right for you.
I've also heard some weird things about the HD 598s in the "Headphones you regretted buying" thread.
EDIT: Nevermind, just double checked. It's the HD 595s taking a lot of flak over there, not 598.
Edited by posteriorpounde - 5/14/13 at 7:43pm