Amarok you are 100pct correct using SP/DIF coax the HP amp is absolutely quiet and clean. This is a very serious piece of equipment for the money.   I correct the original chip was a 2604.   One possibility is if the original chips are not genuine parts putting a known genuine part in...

Does anyone have reason to believe that any of the parts in the DAC are fake? like JRC4558 with 627 etched on them and fake Elna/Silmic caps or are they reputable to be genuine parts?   My standard shipped OPA2134 * (correction 2604) one sounded ok out of the box but no where near as good as...

I think the headphone amp section in this is worth the money in itself, One criticism is the DAC output has a very unclean noise profile (like sizzling eggs) this is very low in level and virtually inaudible at normal listening levels but I would prefer if it was not there. You can only hear it...