All-round Open headphones for around $100

I have the AD700s and the Bass is very recessed. I am looking at getting another set of cans due to it. But they are very tight and have a huge soundstage.

Maybe you could take a gander at the K240 Studio. I don't want to add more confusion to your list, lol. But I really liked these cans, and they were good for all kinds of music, in my opinion. Also, they were easily driven from any source I tried them with. The mids were the best part of these cans to me, but the bass was pretty good as well. I wouldn't call it recessed, but at times it was a bit floppy, maybe a tad uncontrolled. Nonetheless, I really liked these cans.

Also, have you looked at Grados? They're open cans as well. The SR-60 I had was very nice, the bass was there and a bit tighter than the K240. The sound was a bit more, in your face. But personally, I preferred the overall sound of the K240 Studio.

Anyway, just some of my experiences.

I am no expert. That being said I am listening to them right now and love them just want more bottom end for my tastes. They are very bright sounding to me. And very clean in the highs and mids. The bass is almost non existent but what there is is clean but if you try to drive it through an EQ it seems to get pretty nasty fast. They just dont perform that great at lower Freqs. So if you like any Bass at all or punch they are definitely not the headphones for you. IMHO.
 

You can get a refurb HD 558 for $100 from Dakmart on Amazon. I got a pair from them a week ago and am very impressed. Only difference between what I got and a new pair is that mine didn't come with the box. As far as sound quality goes, I've read people say that they have a better soundstage and bass than the two you mentioned. My personal experience is limited, but I can tell you that I like them significantly more than the Koss Pro DJ 100 and the AKG K550. While technically speaking they arent better than the AKG k550 (and since the k550 is $300, they certainly shouldnt be) I still enjoy them much more, even ignoring the massive price difference.

http://www.amazon.com/gp/offer-listing/B004FEEY9A/ref=dp_olp_refurbished?ie=UTF8&condition=refurbished

I havn't used the HD280, but I can tell you that most people on headfi seem to dislike them and find them to not be worth their asking price, whereas most like the HD 558 even at their asking price of $170. Bass on the HD 558 is largely dependent on how good your source is. With a decent amp, the bass should be plenty for rock and probably suffice for techno. Definitely not a basshead can though. I use them unamped but from a retina Macbook Pro, which provides just enough bass for me in most tracks. If you plan on running these from a low end laptop, they probably won't have enough bass.