I still listen in the near field (ears about 55 inches from the speaker drivers), but not longer with the speakers subtending an unusually wide angle such as 90 degrees. I use 60-degree separation, having concluded that, except for the few available quasi-one-point stereo recordings and binaural recordings available, 60 degrees produces a more natural amount of left/right separation. If I want to hear the best imaging and staging from those few recordings, I lsit on the edge of my listening chair and lean in to get a much wider subtended angle between the speakers.
I don't believe that near-field listening and wide separation produce any really substantial amount of crosstalk cancellation. Both ears still hear the sound from both speakers. While distortion from listening room reflections is substantially lessened by near-field listening, that's not the same as actively reducing the sound heard from the left speaker by the right ear and vice versa.
Headphone listening, on the other hand, can produce near total crosstalk cancellation with no electronic processing whatsoever. Closed-back headphones are the best at this. The more "open" quality most listener ascribe to open-back headphones is at least partially attributable to the fact that such headphones produce substantially more interaural crosstalk between channels, though still obviously much less than even near-field speaker listening. And most people agree that the most open-sounding of all headphones are those which do not rest on the pinnae at all, but stand off a bit from one's head, such as the classic AKG 1000 or the new RAAL-requisite SR1a Earfield Headphone. It's odd that with headphone listening the usual electronic or physical manipulation aimed at producing more natural sound has been to reduce (rather than increase) crosstalk cancellation and reduce rather than increase left/right stereo separation. It makes sense, though, since most people want the primary apparent source of musical sound to be "out there" in front of them, not in the middle of the head or panned hard left or right. Locating the apparent sound source out in front has been difficult to achieve with headphones. Some of the best in this respect, to my ears, are the inexpensive NAD Viso HP-50 with Paul Barton's RoomFeel technology which, as I understand it, is primarily the product of meeting experimentally derived frequency response targets.
I have not hear BACCH-SP. However, I've used a few earlier electronic processors over the years which produce unusually wide and/or wrap-around staging through crosstalk cancellation and/or phase manipulation. One of the first to hit the market was Carver's Sonic Holography and I used a couple of iterations of that. Then there was the Hughes SRS processing which I also used (and still use since it's part of the audio in my Sony living room TV set-up), followed by Ambiophonics (Ralph Glasgal). I've used both the barrier approach to cancel crosstalk and the electronic version called XTC which was a "throw-in" processor in the TacT RCS 2.2XP which I owned for a few years.
These systems, while usually impressive on first hearing, can easily wear out their welcome. When "turned up" so as to produce a substantial wrap-around effect, I usually tire of the subtle (or not-so-subtle) phasey "tugging-at-my-ears" sensation which accompanies the wrap-around staging. In addition, there are usually at least subtle (or not-so-subtle) frequency response manipulations. The frequency response effects are not just not subjective, at least not for XTC which could produce very strong wrap-around effects from speakers 20 inches apart 80 inches from the listening position. I measured about 6 to 10 dB of boost in the lower two octaves and a rising high end which was up about 10 dB in the top octave compared to the measured response with XTC out of the signal path.
In my current system (Gradient 1.4 speakers, Lumin X1, Benchmark AHB2 amps) and listening room using near-field listening and 60-degree separation, with lots of dispersive room treatment, but no electronic manipulation, depending on the recording the imaging/staging goes from a narrow point (mono recordings) to substantial wrap around, of between 180 degrees and 270 degrees. The greatest wrap-around effects are generally produced from recordings which have obviously used phase manipulation to generate a bit or more of that "diffuse and directionless" quality you get in spades when your two channels are wired out of phase. Try most anything played on the Deep Space One or Space Station Soma channels of Soma FM.
Quasi-single-point recordings as well as binaural recordings played through my speakers also produce very wide, deep, and sometimes high stages with wrap-around approaching 180-degrees. Such recordings of acoustic music can be both fun to listen to and more "natural" sounding, as in more closely emulating the live concert hall sound you hear from the first ten rows or so where the direct sound of the instruments is "out there" in front but the instrumental sound projects up and to the sides and the concert-hall ambient halo projects up, back, far to the sides and indeed surrounds you.
