I am browsing the Reference Audio Analyzer site and I must say it is quite interesting. Really advanced site build, my compliments.
Anyway, there is something I don't understand in their measurements of the impulse response, which in turns allows for the calculation of the Energy Time Curve for DACs.
Let's take as an example the Hugo TT. this is the impulse response function as
measured by Stereophile
View attachment 223963
It is possible to see very many oscillations there, which is coherent with the Chord philosophy of using a large number of taps. More taps = more oscillations of the impulse response function, and this by definition. Besides that one can see that the filter is time symmetrical and FIR-type.
Now let's see the Hugo TT impulse response function as
measured by Reference Audio Analyzer
View attachment 223967
Reversed polarity, and this might be, but the shape is something totally weird: no ringing. Usually is the NOS DACs which show such a behaviour but Chord proprietary filtering is the exact opposite of NOS. This impulse response function measurement is not compatible with the Stereophile one and seems not compatible with the theory of time symmetrical FIR filters and far away from Chord's approach.
There is something I don't understand here. Any help from anybody will be appreciated.