Speakers better without subwoofers? Crossover and synchronization issues? What do you do

The friend drives his K'temas with a Bricasti Design M25 and I have not heard a dynamic speaker sound better. In this regard I would not change a thing. Up against speakers like Magicos and Wilsons they are dirt cheap and an amazing value. I also think they are cool looking. I also would not add a subwoofer unless you were going to do it right, which means a digital processor and two of the best DACs

@emergingsoul I do believe that is a Franco Serblin stunt. What they are doing is relieving the front woofers from having to make long excursions which lowers their distortion dramatically. This is what subwoofers do when used with a two way crossover and not just the low pass filter installed in most subwoofers. These added woofers are almost subwoofers. That speaker is capable of prodigious volume and they would normally require at least two 15" subwoofers to keep up in terms of getting down to 20 Hz with the required boost. You could probably EQ the Fabers to make that kind of boost, but you would not be able to play the system very loud. So, the internalized low frequency woofer is more a solution to lowering distortion than it is for extended and powerful low frequency reproduction. I have a friend who has Franco Serblin K'temas that do the same thing and they are wonderful sounding loudspeakers. Franco eventually left Sonus Faber to start his own company. He passed away not long ago. Do the K'temas require subwoofers? This depends on your view of the universe. My friend says no. I say yes, but I would cross much lower than I usually do. Large spaces breath at low frequencies. Even with your eyes closed you can tell you are in a large space. You can feel it. Many recordings of live performances have enough of that information present to fool you into thinking you are in a large space, if your system can reproduce it. My system is down 6 dB at 16 Hz, The subsonic filter is at 10 Hz 14th order. From a simplicity perspective my friend's solution is superior. It is much easier to screw up a system with subwoofers than it is to make one better and most subwoofers are not what I would call high fidelity. Have a look at this https://imgur.com/gallery/building-resonance-free-subwoofers-dOTF3cS

@emergingsoul Yup those old speakers were something else. I grew up with my father's Bozaks. The problem is those large enclosures resonate like crazy. They are musical instruments. The bass drivers of the day were not capable of long excursion with any degree of linearity. Modern speakers use smaller enclosures and smaller woofers in multiples. The low bass is separated out and sent to subwoofers which have very specialized drivers able to push out huge bass in smaller less resonant enclosures. 

Many systems are better off without subwoofers, I would venture to say most because the subs are poorly integrated and/or resonate and give themselves away.  In a great system with properly integrated subs you would never know the subs were there until you shut them off.  If you are reading the specs of your speaker, flat to 28 Hz is at one meter. That is a far cry from flat at 12 feet. Not only this but getting realistic bass in a normal size room requires a 10 dB boost at 20 Hz starting at 100 Hz gradually upsloping. Every system can benefit from subwoofers but to do it right requires digital bass management which most people are not using. Integrating subwoofers with an analog low pass filter will only create a result that a seasoned audiophile will cringe at.