Topic: Understanding PreRinging

How much do modern convertors, ala RME's Multiface 2 PCIe et al, still suffer from "pre-ringing ?"

?Pre-ringing,? is illustrated in Figures 1 and 2.
Figure 1 is an impulse, created by setting one sample at full scale and all other samples at zero. The horizontal axis is time; the vertical axis is amplitude. The ?impulse response? of a perfect system would look like Fig. 1. But in the real world, digital filters spread out that impulse of energy over time (Fig. 2). Notice that some of the impulse?s energy appears before the impulse itself. This time smear, which can last up to 2ms on either side of the impulse, is called ?ringing? (the impulse sets the filter ringing as does a hammer striking a bell), and the energy before the impulse is called ?pre-ringing.? Pre-ringing is introduced by the brickwall anti-aliasing filter in the A/D converter, as well as by the linear-phase reconstruction filter in CD players. Although analog filters ring because of the resonant elements in their filters, the ringing always occurs after the signal that set it ringing, never before it. Pre-ringing is unique to digital audio. Think of the impulse as a musical transient. Now think about how bizarre it is to hear part of a signal before the signal itself. Such a non-causal situation never occurs in nature and, consequently, is highly audible.

For images, refer to :
http://www.avguide.com/review/tas-194-m … -cd-player