[MaximumSandvich]

I'm on a pretty tight budget as far as buying an amp goes, and I don't demand extreme volume. Just extreme quality. Will consider anything below $100, but really trying to get one for under $50.

 

[Bill-P]

I think the DT990s seriously need an amp that can roll off high frequencies and provide some warmth, otherwise they are ice cold and almost anemic sometimes. That almost practically rules out any amp below $50.
 
What kind of music do you listen to mostly?

 

[MaximumSandvich]

I've decided sub-$100 is my price range. Thinking of getting a fiio E7. Mostly power/progressive/melodic metal.

 

[PurpleAngel]

You said your looking for a portable amplifier.
The Fiio E7 is a DAC and an amplifier.
Where as the E11 is just an amplifier.
What are you going to be plugging the amp or DAC/Amp. into?

 

[Bill-P]

If it's extreme quality under $100 for amp, I think the CmoyBB and Fiio E11 are pretty hard to beat.
 
Fiio E11 sounds clean and clear with an apparent constant-on bass boost. In my opinions, it'll pair well with instrumental songs, but less so with vocals since it can sound a bit too cold or dry with the DT990. And to be fair, that's more a fault of the headphones than of the amp.
 
CmoyBB, on the other hand, is pretty decent with any genre. Out of the box, the Fiio E11 may sound superior, but if you are willing to invest in rolling/replacing the OpAmp then the sky is the limit, really. Personally, I have tried the CmoyBB with as much as a dual OPA627AP OpAmp. Barring the technical mumble jumble, the bottom line is that the CmoyBB can sound very good, and I think that once you start rolling the OpAmp, CmoyBB may well be the best portable amp you can get for under $100.

 

[MaximumSandvich]

Ordered the Fiio E7, since I want to be able to take it with me. Should be getting my Beyerdynamics and the amp at around the same time next week!