I think he said he wanted something under $100. I have the Magni with the 990 pros and I do not like it (using Music Streamer II as a DAC). There are a number of reports of the Magni extending the highs and lows in ways that you don't really want with these particular headphones. Obviously the Lyr and Bifrost is great if you have about $1000, or so to build a great setup. But the Lyr has tubes, and it was designed specifically with the 990 600-Ohm in mind, apparently....
If you want a decent cheap setup for music, I recommend the Fiio E-10 dac/amp. It has a really smooth sound and sings well, especially when you have it on high gain and bass boost. I don't know how well it would do for games, etc., but I really like it as a cheap setup.
I think other Fiio products are probably good with the Beyers, as the Beyers tend to be a bit hot on the top and bottom, where Fiio tends to be warm in the mids and a bit rolled off on the highs.
Otherwise, yeah, if you want to get into tubes, that's what a lot of people recommend.