Originally Posted by ap1
You can hear differences in digital filters. Otherwise we won't see DACs where you can choose filter out of 5-10 available options.
That general kind argument is easy to criticize. It's like saying that since there are six brands of white general purpose flour on my supermarket's shelf, they must all make different-tasting bread. In fact we know that white general purpose flour is a highly generalized commodity, and that there is a good possibility that two or more of the bags contain flour that was packed in the same factory from the same flour storage bin. There might even be bags marked as if they were different types of flour, that are in fact the same.
When someone says that he can hear differences in DACs, in most cases iteans difference in digital filters.
One of my advantage on you is that I am aware of and have participated in listening tests involving relevant alternative kinds of digital filters. For example a digital filter can be:
1. Linear phase 'soft knee filter'
2. Minimum phase 'soft knee filter'
3. Linear phase Brickwall filter
4. Minimum phase apodizing filter
5. linear phase apodizing filter
and in a DBT they are all indistinguishable.
The reason is simple - in every case the artifacts related to the type of filter are at supersonic frequencies or frequencies that are above the range where the ear is sensitive to phase shift or transient response differences of the kind that are actually observed with these kinds of filters.
You can have scope traces that come from all sorts of different directions, and it can easily all sound the same.
A more likely explanation for the existence of DAC chips with different kinds of digital filters is that they were created to be more salable, regardless of their actual sonic properties which are all probably very good and therefore indistinguishable.
Consider this - why would someone risk building a DAC that would sound bad if some button were pushed by mistake?
It doesn't take a lot to make a chip that implements a number of different kinds of digital filters. There are now cookbook design tools for working out the actual circuit parameters. If manufacturers can get the "design-in" or the audio store product sale in this highly competitive market, its all gravy.