DSPeaker Anti-Mode X4

I really haven't talked with others with experience using the DSPeaker Anti-Mode X4 in a system where listening is done from the far field. I see no reason why the X4 would not prove equally transparent in such circumstances. I also don't think far-field listening would impair its ability to smooth the measured and subjective frequency response at the listening position, but that's just a guess, not something I have from direct experience or even reports of others.

I have listened in the near field rather consistently in my listening rooms for decades. I encourage everyone to listen near-field. You really don't know what you have, speaker-wise or recording-wise, unless you do. Eight feet or more back you are largely listening to your listening room's small-room acoustics rather than the frequency response or space (real or artificial) actually captured on the recording. Room treatments can reduce that problem, but not nearly as effectively as when one listens near-field.

While you are correct that listening in the near field gives you less of the second venue effect of overlaying your listening room's acoustics on the sound captured in the recording, the gains produced by near-field listening are primarily in the midrange and highs. The room's bass modes are not negated much by near-field listening, at least not until you get to somewhere really close to the speakers, like one meter away or less and even I don't routinely listen that close up.

Part of good system set up is to find spots for the speakers and listener which work well in your particular room with your particular speakers in terms of producing as smooth a bass response, with as little sharp reflections of mids and highs from room surfaces as possible BEFORE applying electronic equalization. Thus, with good set up, the speakers are aimed away from the walls and toward your ears, absorption and/or diffusion is used to treat all room surfaces near the specular reflection points of the speakers as viewed from the listening position, and the distances of speakers and listener from floor, walls, and ceiling are all carefully adjusted. With speakers which, like my Harbeth M40.2s, have inherently quite smooth mids and highs, given such set up, the room treatments basically take care of mid and high frequency problems.

That leaves the bass. Careful positioning of speakers and listener can smooth bass response quite a bit. Still, even with careful positioning of listener and speakers, in many rooms, especially with speakers with generous bass response like the Harbeths, you will still need electronic equalization to smooth the response below 200 - 300 Hz or so, to allow evenly tempered bass lines and elimination of the dreaded "one note bass" problem. And in my experience all electronic equalizers work best in correcting the bass range when they have as little to correct as possible.

Still, as noted in my comments, with the X4, even in my near-field set up allowing the X4 to make very minor corrections above 500 Hz seems to further improve the sound of my M40.2 set up.

Smoothing frequency response at the measured/listening position also usually works toward correcting phase response at that spot. Thus, I see no reason why the X4's equalization would adversely affect the phase response at the listening/measuring position of any speaker. That applies for any equalizer, whether used in the digital or analog domain. The idea that equalization somehow messes adversely with phase response is an audiophile old wives' tale.

Speakers like the Vandys and Thiels which produce time-correct impulse response at a small well-defined position (the primary listening axis) usually fall apart tonally and phase wise away from that axis. The room sound is thus more of a mess both frequency- and phase-wise than with many ordinary speakers. See, just for example, the off-axis frequency response of the Vandersteen 7 in figure's 6 and 7 of the measurements section of Stereophile's review here. This makes perfect sense since the very means of creating that in-phase on-axis response--physical offset of the drivers and first-order crossover networks--mean that from the side the drivers are definitely not lined up in such a way as to produce a time-coherent wavefront.

I do think that the Z-Systems rdq-1 is better sounding than the Behringer DEQ2496. I used both exclusively in digital in/digital out configurations. Both have significant learning curves and for best results both require using an external measuring program to know what you are doing, although the Behringer does have some auto-EQ functions which work reasonably well. But while I thought the Z was highly transparent apart from the desired frequency response change, I thought the Behringer added noise as well as transistory nastiness to the highs. I would go with the rdq-1 if you can find one and can afford it. See my comments

My other thought is that you could attack your excess high frequency problem either via room treatment or changing your speakers. Thiels were designed with an unusual definition of flat high frequency response. They are "flat" even at considerably off-axis angles. This causes a lot more high frequency reflection off your listening room walls than with many other speakers and thus will tend to sound irritatingly bright even though they may measure flat on axis rather than rising in the highs. You could add absorption, such as in the form of fiberglass or foam batts to cover those wall sections near first and second reflection points of the speakers. Or, you could just swap speakers for something like Vandersteens which like the Thiels have "time coherent" crossovers, but generally sound fuller in the midbass and less bright in the highs.

No, I have not heard the miniDSP units. My need for a separate DSP equalizer has evaporated since I now use both Roon and the Dutch & Dutch 8c speakers. Both have on-board parametric and other DSP equalization capabilities. My current systems are detailed at this link.

And, in my room with the 8c speakers set up as I currently have them, I hear no need for EQ beyond the basic 8c settings corresponding to their distance from the wall behind them and the nearest side wall. I have tried further smoothing the measured frequency response (I use OmniMic V2 for measuring) using the 8c DSP parametric EQ, but hear no improvement from this exercise. The D&D 8c speakers in my room with my current set up yield truly fabulous results "right out of the box"!