Headroom promotes 'voodoo' reasons, for the most part. They sell all sorts of meaningless 'upgrades' for their amplifiers, on special swappable circuit boards. They make baseless references to their balanced amplifier having better sound than an unbalanced one. They sell very expensive amplifiers on the basis that they sound better. If they really do sound better, it would probably be because they intentionally distorted/altered the responses from the lower lines. But that seems unlikely. I have not had their products in order to measure/analyze them, therefor I don't know how their products perform. They make other dubious claims also, but I am just giving a select few.
It's perfectly valid to buy the expensive stuff on the basis of pride and ownership and overall subjective enjoyment, or perhaps actual distorted output[to get a specific colored sound], but headphone.com is full of unsubstantiated information. Unfortunately, based on the apparent poor level of comprehension related to amplifiers and cables vs. human perception, one can not trust them to comprehend other issues, either.
-Chris