Seems like a common topic, but everyone is looking for something different when it comes to amps for these headphones, myself included. In my case, the $360 expense* for the headphones themselves is the reason why I didn't buy them years ago. The simple fact that I pretty much must complement them with an amp of some kind is almost a deal breaker for my poor finances.
*(Somebody mentioned in the "seeking advice" thread that these headphones can be had for under $300. I'd love to know where!)
I already tried researching this. What I came up with:
FiiO E7 USB DAC and Portable Headphone Amplifier
Pros: Fits my budget. Heavily associated with the HD650 on Amazon - people seem to like it. No major flaws noted. Bypasses the use of a DAC in the PC itself.
Cons: 16bit 48Khz cap. This means that the noise floor is unavoidably high, which would seem to defeat the main points behind both the use of a USB DAC and the use of high-quality headphones. Also, I can't pin down this device's latency, which is a problem with all USB DACs. I plan to game with whatever I end up buying, so latency is a no-no.
Nuforce Icon uDAC2-HP Headphone Amp and USB DAC
Pros: Fits my budget. Mentioned in the same breath with the FiiO E7, though regarded as better, if less flexible. Bypasses the use of a DAC in the PC itself. 24bit 96KHz.
Cons: Tons of people have complained about a high-frequency whine produced by this device, and I suspect that it is an inherent, universal flaw. This basically means I won't be buying this.
Xonar Essence ST
Pros: I could stretch my budget to make this fit if I had to, but it would slay me. In this thread: http://forums.overclockers.co.uk/showthread.php?t=18211138, one fellow gushes over the combination of this card and the HD650, and later on, somebody who can afford the HD800 and other expensive hardware offers his opinion that a proper headphone amp probably would not give any real improvement over said combination. That carries a lot of weight with me. Also, since it is a soundcard, I could expect effectively no latency, which means it easily beats any USB solution.
Cons: It's a soundcard, and I have never experienced a soundcard or other internal DAC solution which didn't let internal noises bleed into the audio (for example, power fluctuations associated with drive activity).
HRT Music Streamer II High Resolution USB D/A Converter
Pros: Fits my budget, sort of. 24bit 96KHz. Asynchronous USB mode (for the win).
Cons: Latency unknown. Not much discussion about this product. I only discovered it ten minutes ago myself.
That's about all I've been able to round up in the last couple of days. Whatever I buy, it will be used on a desktop PC, so it doesn't need to be portable. As mentioned before, latency is a significant concern as I will be doing a lot of gaming, plus latency just plain bugs me. I basically just need to know if anyone can make some suggestions based on the trend of the contenders I've submitted. If there are any points I forgot to clear up, please ask. Thanks!