There's that, I'd think a nice tube amp would match the k701 well. I like tubes with my dt 880s very much!
or trying going with an Odac [with rca out[ and one of these
Porject Starlight, new from them for about 189, they are the same guys who make the Project Sunrise II which I've heard alot of good about. So if u able to wait, get a 100 dac and look for a 200 hybrid tube amp! I have a Millet Whiplash that I like very much!
I also have an Indeed G3, which cost me $100 that's,,, well a start hybrid tube with a BASS boost button. That might be the cheapest way to go. Still though, I would think a tube would match the k701s well, as my neutral and some times bright dt 880s like tubes