I suppose the argument about 1st order vs. higher filter will go on forever. Too bad there are so few (besides Vandersteen I don't know who else) actually make 1st speaker so people don't get to listen and understand the actual sound so they end up instead hearing from magazines who don't understand themselves. Of course magazines have there own agenda so who knows if they tell the truth.
I've had this little exchange with someone who has been designing speakers as if his life depends on it. And we are trying to “objectify” why the difference and we both agree that the biggest difference is how the high frequency or to be specific the treble is reproduced. With 1st order, the treble is part of the music whereas with higher order filter, and we actually agree that higher order generally has a cleaner, clearer music reproduction, the treble seems to be riding on top of the music, instead of being integrated within the music like 1st order.
And since the treble is where lies the most differences, what he does is that for example with three way speakers, the xover between the mid and the tweeter, he would use first order. The xover between the mid and the bass which is around 400hz, he would use 2nd, and since the wavelength at 400hz is so long, the phase does not matter much, and of course, 2nd is much easier to implement vs. 1st. This is consistent with speaker design in which at the low frequency such as the bass, amplification quality is not as important and as said above, our hearing is not that sensitive in the low frequency due to the longer wavelength. Most sub woofers if not all using digital amplification since using linear amplification probably does not make much of a difference. Try using digital amp for your tweeter :-)
Interestingly, after listening to 1st speakers for awhile now, I seem to attribute the sound to that of tube amplification. There is something to 1st order sound that is similar to tubes. And I don't think that is a coincidence either. Tubes have a way to deal with treble better than transistors. Transistors although always sound cleaner and clearer, compared to tubes, but they always sound somewhat clinical and analytical compared to tubes. I won't go into detail as to why since it may take quite a bit of spaces with all the technical stuffs that might drive prof crazy.
This leads me to something a bit analogous to what have said above with a slight twist. I currently have two preamps – one is a Pass Labs X10 which is transistor-based, and the other is a Conrad Johnson 17LS which is tube. Both are very good in their respective domain. The X10 is actually very smooth and warm and fluid in a transistor sort of way. The 17LS is a touch bright and extended vs. the X10, so you would think I would hear more “treble” on the 17LS, but that is not the case, because with the 17LS I just hear music because the treble is so well integrated with the entire musical range. On the X10, although sounding a touch warmer vs the 17LS, I would hear the treble somewhat sticking out like it is “riding on top of the music” as I have mentioned above. BUT here is the KICKER. When I design my speakers, I always use the X10 to fine tune my speakers because the X10 is more neutral and it is able to tell me the strength and weakness of my speakers better than the 17LS, and it allows me to better optimize my speakers xover. And of course with better optimzied speakers, I can enjoy them better with my CJ 17LS :-). So I guess it's a complementary, symbiotic thing.
A lot of time, with music and our hearing, things can get a bit complicated and people can get overly emotional, but there is something analogous to “sound” that can be more easily be “objectified” and generally agreed upon. And that is the physics of “light”. As with sound, it is frequency dependent. For example, lower frequency light tends to be reddish, whereas higher frequency light tends to be more bluish. And as analogous to sound, a image that has a lot of low frequency, it tends to be a bit less “sharp”, and likewise, an image that has a lot of high frequency content, the image will appears sharper and clearer.
Most people at one time or another have bought a brand new television set. The first thing you do when first receiving the TV is probably adjusting things like contrast, sharpness and so on. I am using “sharpness” as an example. So when you want more sharpness, what the TV would do is using a high pass filter or amplifying the high frequency range (similar to the high pass filter for the tweeter) so you get more high frequency and more bluish tonal balance on the picture hence a sharper image, just as the sound will get more clear if you have more treble. And of course as with sound, if the image gets too sharp, it can be “unnatural” similar to treble fatigue.
I am not an image processing engineer so I don't know the detail of image filter design, but someone told me that they actually face with something similar in speaker design, such that if they use higher order filter, the image can get “unnatural” albeit having more clarity. I suppose if you were to design a spy camera to search for weapon of mass destruction, you probably want to use higher order filter :-)
Anyway, back to speakers design with 1st or vs. higher order filter. Interestingly enough, if I were to run an audio recording studio, I would use higher order speakers to monitor the recording sound since I think higher order can tell me more about my recording sound, but when I go home, I'll use my 1st order speaker to enjoy the music. We human are yin and yang. Duality works.