These are K81dj killers...the caveat being that the K81's will give you more isolation. But these are just the total package. They look cool, have a shorter cable, closed, aren't isolation champs, but give enough isolation to be useful, have a good soundstage and good sound quality for the price.
In fact, maybe better than good SQ for the price. I'd rate them as closed MS-1's. They're not bright and harsh (well, they are closed ms-1's so if you found those bright...), and the mids aren't any more recessed than any other closed headphone, so all-in-all, they're keepers. I'd say the bass is a tad big, and that colors the entire sound towards the darker, but it's not as big a problem as say, the ath-fc7. Not by a long way. No, your ears adjust to it and for portable use, yeah, it's fun.
It doesn't need an amp. The bass tightens up a little bit if you use one. I use these for trips into the city, where I have to put on and take off the headphones all the time. Then once I'm gonna have headphones on for a while I switch to Sensas. So obviously the worst of their flaws come out when you first make that switch, but your ears will adjust. I happen to use the Hornet since I was already using it with the Sensas anyway, but you don't need to buy an amp for these. The sound is full enough without. In fact, with less bass impact sans amp, you may prefer it without.