I don't think that is a DAC or an AMP, it's just for surround which you most certainly don't want on a pair of stereo K7XX's.
What would be your budget for a DAC/AMP? For under $100 fiio E10K like you already mentioned is pretty good, I had one for my HD600s and it worked great until I broke the headphone jack and only one channel worked. If you do get the E10K I would be careful with the jack, it's not exactly robust.
I have a more expensive "schiit stack" now, which consists of the schiit magni and modi. Thats about $200. I also looked at the mayflower Objective2 and ODAC, that's about $230 and is pretty highly regarded from my research.
Yeah that's just a virtual surround device. It's not going to drive K7XXs. E10K, Schiit Fulla 2, Fiio Q1 or better the Q1 MK II. What's your budget? As Dunlop0078 mentioned a Schiit stack or an O2/ODAC ( I have a Mayflower O2/ODAC Rev. B ) would be better. Price just goes up from there.