I've read that some ESS-based DAC's don't have it. One possibility that comes to mind is that they're using different filters, either selecting them on the chip or their own, but I'm not sufficiently familiar with DAC design to know.
Here's what Keith L of Emotiva had to say about it. It jibes with my guess that it has something to do with the intentionally underdamped impulse response:
'The signal passing through a DAC is often altered in many subtle but significant ways... many of which involve timing.
However, most of those alterations are somewhat complex to measure, and
VERY complex to interpret.
If you look at the analog output of several different DACs with a variety of input test signals, you will see significant differences.
Many manufacturers and magazine reviewers publish certain of these characteristics - like "impulse response" - and those measurements are in fact different for Sabre DACs than for most others.
Unfortunately, even when looking directly at the images of those signal characteristics, it isn't always obvious what a given difference represents in terms of
SOUND.
'What is happening is that Sabre DACs have certain differences from most other DACs in terms of how they handle some sorts of impulse signals.
Because we're talking about subtle differences, and because no current DAC is perfect in this context, it may be difficult to suggest which ones are "more correct".
(Most of us here at Emotiva agree that the DACs we've chosen to use produce an output that we perceive as being more accurate to the original than Sabre DACs.)
However, if you compare oscilloscope images of certain test signals, the differences themselves are relatively easy to see.
And there are certain commonalities in how they are perceived by the majority of human listeners.
'When comparing a Sabre DAC to "an average DAC" from any of several other brands (with similar basic specs).....
- Some listeners fail to notice any significant difference
- Most listeners who notice a difference and
LIKE Sabre DACs describe them as sounding "more detailed" or "more revealing"
- Most listeners who notice a difference and
DISLIKE Sabre DACs describe them as sounding "etched" or "grainy" or "bright" or even "overly detailed"
'Regardless of which group you agree with, it seems somewhat obvious that the same general characteristics are being described by both.
Note that the surrounding circuitry has a major effect on how a DAC chip will sound... and different products that use the Sabre DAC chips seem to exhibit this characteristic sound to different degrees.
(However, it would be accurate to say that, in most situations where someone does notice a difference, this is the way they describe it.) '
http://emotivalounge.proboards.com/thread/52163/sabre-dac-glare-frequency-range
Interesting, no?