Coincident Pure Reference "Extreme"
www.high-endaudio.com

The "Extreme" is simply the "Original" Pure Reference, with the exact same drivers and crossovers, but in two separate cabinets (a mini-monitor and a subwoofer), instead of one large floorstander. With the monitor sitting directly on top of the subwoofer (at the front), the Extreme is around 12" shorter, though its subwoofer takes up around 50% more floor space, because it is 4" wider. The price for the Extreme is $ 26,000, compared to $ 22,000 for the Original.

I have around 100 playing hours on the Extreme, and all of it with the Coincident Frankenstein M300B II amplifier. Based on the experiences of others, it will further improve with more hours, but not dramatically. The big questions are how the Extreme compares to the Original, and whether the $ 4,000 price differential is worth it (since the Original will still be available). First though, I would advise those seriously interested to read, or at least skim over, my Review of the Original Pure Reference. This should help the reader to fully appreciate the sonic differences between these two (otherwise) similar sounding speakers.
Now, as to its performance...

The Original Versus the Extreme

The Extreme is superior to the Original in a number of areas, equal in others and inferior in none. A typical "neighbor", or "brother-in-law", would not be able to distinguish one speaker from the other, but any experienced audiophile should easily hear the differences. In every instance, but one, the sonic differences between them are minor, meaning they are "noticeable", but not "obvious", unless you are an exceptionally discerning listener, or are intimately familiar with their sonics (as a normal long-time owner should be). I will deal with these minor improvements first.

The Extreme is a little cleaner and faster than the Original. The purity is more easily noticeable at higher volumes, but is still slightly audible at lower volumes. The Extreme sounds even more like a top electrostatic, such as the Martin-Logan CLS (in its greatest strengths), than before. While its overall tonal balance, perspective and neutrality are the same as the Original, the Extreme does have a small reduction of those tiny frequency aberrations which are unavoidable in every speaker. These deviations are too subtle to even describe, but they still inform you that a mechanical device is reproducing the instrument, rather than it being the real thing.

As for the frequency extremes, the highs are the same, though the bass appears to be just a touch more extended, and with a little more weight and body to it. The quality of the bass is also slightly improved, being, once again, a little more articulate, controlled and defined. The quality of the highs is also better, but it's even more subtle. This time, a very tiny resonance, only barely audible with very specific frequencies (flutes, violins and sopranos), has now been effectively eliminated. (Since this resonance was slightly more noticeable with the Ars Acoustica System Max, I wasn't able to isolate the cause of the residual problem when I heard it being reduced.)

I saved the best for last, because there is one area that the Extreme is significantly superior to the Original: Image Focus. In my lengthy review of the Original Pure Reference (PR), I mentioned that my ultimate reference for image focus was the Morrison, which is an omni-directional speaker. Just behind the Morrison was the Ars Acoustica, which is the speaker that the PR replaced. The PR, as good as it was, still noticeably lagged behind both of them. This is no longer the case. Now the Extreme equals the Ars Acoustica. In fact, it's so similar to the Ars in focusing, it's almost spooky (I lived with the Ars for 10+ years, and just heard it again in June 2009).

There is one small difference between them though, and it's actually in the Extreme's favor. The Extreme is slightly better focused at the lateral extremes (to the left of the left speaker and to the right of the right speaker) than the Ars. In fact, the Extreme is as good as I've ever heard, even including the Morrison, at the outer edges of the overall soundstage. (The Morrison is still the "champ" in the large middle.) I don't believe the soundstage itself is any larger, but it is better "organized", so it may appear larger because it is more easily "seen" and "understood". This brings us to the second "big question":

Is the Extreme worth the extra $ 4,000?

This question can only be answered by how much you value the various improvements. In my case, the improved image focus alone makes it worth the extra money, with the rest being "icing on the cake". The bottom line for me is simple: I can't go back to the PR.

Other audiophiles, who don't value "imaging", may have a very different perspective. In fact, unless you truly value imaging, then I would most likely pass on the Extreme, unless either:
1. You just must have that last degree of purity, speed and detail etc., discussed above, or
2. The added flexibility of having two separate cabinets is important to you, especially if you want to "double up" the speakers one day, and/or place the subwoofers elsewhere in your room, while optimizing the position of the monitors on their own.

Then there is one last question: What if you already own the Original PR? Should you spend something like $ 10,000 to trade up? Frankly, I don't feel it's worth it, unless you are an imaging "enthusiast", meaning someone who is actually bothered by the PR's imaging performance, but otherwise satisfied. Other than that, the differences I've described are just too minor to justify that kind of money.

Conclusion
The Extreme is a welcome improvement over the Original Pure Reference. If I was to asked to make an analogy, I would say that most of their differences are the equivalent of "turning a page or two", while the Image Focus improvement is the equivalent of an entire "new chapter". In the final analysis, the Pure Reference, in its Extreme form, is another step closer to the music, and a step further away from the "mechanics".