Dunno if a half-rack unit would suit you, but ART has a new half-space 5-output headphone amp for $79-ish. Sounds just fine - then again, so does the behringer.
Honestly, at this price, I don't think anything is going to be signinifcantly better, or better made, than the behringer. Not that I'd go out of my way to recommend it, mind you, but it's just that there's nothing else on the market that's particularly better or worse. I've had that little rolls amp, too, and it sounded/performed exactly like the behringer. You've gota figure that any headphone amp in this price range is, pretty much, disposable. Even in the audiophile/hi-fi world, a good headphone amp is a rarity.