I LOVE my FiiO E10K Olympus 2 DAC/HP Amp! And it was only like $130 or so I think? Drives everything that I own pretty nicely, and I've been looking to pair some HQ cans with it soon! Oh and it's TINY! It drives my Sony VA15 speakers very well and I will definitely continue to use FiiO products for their amazing price and sound quality! I've liked their stuff since I bought a small FiiO HP Amp many years ago for $30
It's a shame that Tonedeaf isn't here on ts.com any longer, because he owns both the Senn HD6xx AND a FiiO HP Amp, so he could really tell you how the two pair together
But for under $200, a FiiO DAC/HP Amp would be a great and tiny solution IMO, and won't take up much space at all around your computer!
I also own and OFTEN use a FiiO E11K Portable HP Amp! Best $200 I've spent in awhile buying the FiiO E10K & E11K a couple of years ago!
Here's a pic of the FiiO E10K DAC/HP Amp next to a regular size Bic Lighter to see how tiny it really is. It's smaller than a pack of cigarettes