Note that the DualCore operates primarily by reducing peaks. Room resonances (modes) usually manifest themselves as peaks. But since the system quite correctly operates by removing such resonant peaks, it is possible for the overall bass level to drop too much, especially in the “Typical” mode of operation with the filling in of dips turned off completely (and even more so with “No Compensation” for dips). Note that recordings are usually made with the expectation of some bass lift in-room: Literally flat response tends to sound lean.
In any case, the DualCore offers several ways to deal with this question of overall quantity of bass. First, as already noted, there is the choice among levels of dip filling in. A choice of “Typical,” “Maximum,” or “No Compensation” is likely to come out quite close to right. In addition, there is a feature called “Quicktone,” which is in effect various versions of the “tilt” controls made famous in analog form in Quad preamps (linear phase correction here). As also mentioned above, you can also insert a custom “House Curve,” which shelves the bass up below a userselectable frequency. There is also a more subtle way of dealing with the issue by judicious choice of the upper-limit frequency of the bass correction. This is again user-selectable.
The “calibration” is done on the summed response of two channels in the true bass. This makes sense because real bass tends to be perceived as a summed event as far as amplitude response is concerned (this is why one subwoofer works as well as it does).
You can also use the full-range measurement feature (a sweep measurement of in-room response) to check the general integration between the lower and upper frequencies. This provides a useful check on the choices discussed previously.
Note, however, that if you want to use this measurement for setting parametric EQ (see below) then you should do the measurement quite close to each speaker. This type of measurement, which gives the steady-state response, should not be flat in the higher frequencies at the listening position—smooth, yes, but not flat—but rather should slope down somewhat with rising frequency if the measurement is done at any substantial distance from the speaker. (Audio people tend to assume that any response measurement ought to come out flat, but it is the direct arrival of a speaker that ought to be flat in the higher frequencies, not the overall room sound. Measure up close for the frequencies above the bass and lower mids!)
As you see, there are a lot of ways that one can vary the detailed results of the bass correction. You should be uninhibited in experimenting with them. The whole point of all these settings and options is to let the ear be the final arbiter, as Lord Rayleigh famously said. And it is indeed useful to set up a number of options for comparison. Such comparison is easier than might be expected, because you also save various choices (“profiles”) for quick comparisons. You do not even need to recalibrate each time—you can copy a given profile into another profile setting, modify it, and then save it as a new setting. There is in addition a measurement feature that does a full-range frequency sweep so you can see how the integration of the bass correction and the frequency range on up to the top look, for example.
Clearly we are getting into a little more sophisticated set of operations now, but this never gets hard to do. This is one digital system where you will not need any outside help to get rolling—or even to get things as perfect as possible. With the easily comprehended menu, the measurement feature, and your own ears, you do not need an outside expert. Trust your ears and experiment!
More possibilities: Parametric EQ
So much for the bass. But there is yet another set of EQ settings that play an important role, potentially. The DualCore allows the user to make as many as sixteen “parametric” EQ filters, with selectable center frequency, amplitude (of lift or cut), and “Q” (width of the correction—high Q is narrow band, low Q is broader band). The device presents the bandwidth of the filter as the datum, not as Q as such. This is primarily of interest in correcting the speaker itself, though you can use it to modify the room correction as well.
As already discussed, the room affects the sound of higher frequencies less than lower frequencies because the ear/brain edits the perception of sound to emphasize direct arrival in the higher frequencies. But no speaker is absolutely perfect and most can benefit from a little touch-up—or more.
Many speakers, even high-end ones, make surprisingly large errors in response in the frequencies above the bass. And even the best can be tweaked to be better, with very few exceptions. (You might want to look at the first figure here, www.regonaudio.com/Digital%20Correction%20for%20Audio%20Part%20III.html showing what just four parametric EQ filters between 2kHz and 8kHz could do for a speaker that was already quite flat. There are very few if any speakers in the analog-only world that are as flat as this in the range that was corrected. And that is only four filters in action: The DualCore has sixteen available.)
This is a different world from purely analog speaker performance, different and better. (The corrections in the link given were actually done earlier with the Z Systems rdp-1 parametric EQ device, but similar results will be obtainable from the DualCore, parametric EQ being a mathematical and uniform process.)