Best solid-state amp for HD 650 under $400?

Rather than buying another headphone, I'm wondering if getting a better amp for my HD 650 would be better.

Right now I have an NFB-12, which I understand has a good DAC, but lackluster amp? I have a few questions:

1) Is it possible to have an amp that is somewhat brighter than the NFB-12's amp, to pair well with my darker HD 650?

2) Would upgrading to a better amp and using my NFB-12 as a DAC really noticeably improve sound quality, detail, etc? Or, is my NFB-12 already powerful enough that there shouldn't be a drastic improvement to be noticed?

3) (Most importantly:) What would you recommend as the best solid state amp for the HD 650 to pair with my NFB-12 as a DAC, that is roughly or less than $350?

Also I don't want tube based amps because I don't want to ever have to replace tubes. I don't quite understand why people recommend tube amps for the HD 650, because I thought tube amps were dark/veiled, which combined with the HD 650 would seem to double the darkness.

If possible, as a bonus, it would be nice if there was a <$400 amp that would do some justice to the top-end headphones like LCD-2's if I ever decide to upgrade headphones, but I suppose that's unlikely.

Well here's what leads me to think something is wrong. I recently got the SRH-940, and quite frankly they just seem better than the 650's when it comes to well-recorded jazz, female vocals, complex sounds from acapella singing groups, and some other things - which I thought people said the HD 650 is excellent for. I believe the detail is there in the HD 650, but compared to the 940, jazz and female vocals simply sound comparatively "veiled" on the HD 650 which isn't necessarily a bad thing I guess, but slightly more detailed would be nice.

I hear again and again people raving about the 650 even against things like the HD 800 and electrostatics (which I thought were super revealing), and it perplexes me because this is not what I'm hearing. I'm hearing a great headphone with great bass and nice detail, but as mentioned the SRH940 ($300, low impedance) wins significantly (in terms of detail) in some genres that the 650 is supposed to thrive at.

I'm not really interested in DIY or tube amps.

So the Yulong D100 has a better DAC and a better Amp, most likely? Will it run an LCD-2 well?

So HDP is recommended for darker phones like my HD 650? How is the DAC? Is it better than my NFB-12's dual WM8741s?

I think the main problem I might have with my NFB12, if any, is that it has a dark coloration which adds to the HD 650's already dark color.

Well then, any recommendations of a good way to EQ (analog vs. digital)? All software EQ I've tried introduces clipping and reduces resolution (sounds like quantization issues).

Software equalization inevitably introduces quantization error, but maybe the error won't be noticeable if I can avoid the clipping by just turning things down. I'll try it when I next get a chance.

Another big issue is that only one computer I have (the one I don't usually use for music) supplies an equalizer at all (provided by the default sound drivers), and music player EQs don't work because I play a lot of stuff from grooveshark.com.