What makes a DAC so expensive?

If it results in distortion then it is measurable. If it is above a certain level it will be audible. If it is audible then it’s a lousy DAC sell it to an audiophile and move on. DACs that are well engineered DO NOT have sound signatures they are considered audibly transparent
I hate to break it to you, but no audio equipment is 100% transparent.

:)

I am an audiophile and i said all that a few post ago without insulting all these people who lives by the book of measures or any book........

Noone ever claimed any DAC was 100% transparent. I said audibly transparent. I never claimed transparent is what everyone wanted I was trying to answer specific questions about audible distortion and power supply noise.

"Synergy" is actually a potential problem when establishing high end systems.

It is a good example of my dictum; The greatest impediment to advancing an audiophile system is the audiophile.

I encourage people to roll this around in their mind a bit before responding with a knee-jerk reaction. 

They aren't even audibly transparent.

They aren’t even audibly transparent.

Some are more audibly transparent than others.... It is a relative quality for which the criterial judgement is linked to the perception of a tonal timbre instrument accuracy....

The more accurate an instrumental timbre will be the more transparent the dac will be....

"Ideally" a good dac disapear to let piano or violin only in existence....

Numbers means something for the designer work, but it is the designer ears who judge at the end....Not numbers written on a white paper ....