I really do not think your tone will work out here. Nothing in this world can be that absolute.
You are entitled with your own opinion, and I respect that.I also heard that many people say you need a speaker amp to power the HE6.
However, whether or not I will put aside my HD800 will not be depend on your taste. It is like saying HD800 is better than T1, or STAX is better than HE90.
Base on your very expensive collection on headfi systems, I do valid your feedback on those amps, but I really think you should also provide more details other than personal expression like "thin" in sound.
I have read about your claims about those "MAGIC" boxes. I really think you should layout more background about your findings. Otherwise, it is very hard for people to understand or believe you.
I am sure DACs been make recently all have USB async board built in. They completely change the story about jitter. There is no clock signal been attached anymore meaning you do not need to have ultra clear signal anymore. The jitter has more dependence on the DAC's on board converter as compare to the external one.
The main reason that we switch to digital representation of the signal is to make it more robust to noise and interference. Hence, I really think if a $500 USB cable is going to improve your DAC's sound, the DAC design is having some serious flaws. In the end, you are just reading something that is either "HIGH" or "LOW" with a very large voltage range for the noise to play around and not casing any trouble.
Let just say even some jitter has been produced in the DAC, how many of them can be hear by human ear is another story. If you have done the GOLD EAR TEST presented by Phillips, you should notice that even telling the difference between 128Kbps and 112Kbps mp3 files are very hard for most of people without training. How hard can it be for you to tell the difference between a 24/192 recording and 24/96 recording? I personally do not have the confidence to say I can ace it 100%.
I admit, even though I can pass the GOLD EAR TEST, my ear is far from a true GOLD ear in headfi. For instance, I can not pick up any difference between a $2000 cable and $200 one. I also cannot pick up any jitter difference between my USB and Optical interface on my DAC. I think my ear is only good for HD800 "level of details" and anything higher for me is "useless" to me. You have to believe that in this world, there are people that is "worse" than you. They just do not "deserved" the ultra expensive stuff currently on the market now. Anything that is obvious to you, might not trigger anything to others.
MAYBE I am just NOT AT YOUR LEVEL.