what is the best super speaker and why?

You know, I just re-read my post and it sounds like I'm really slamming those speakers. Not so...at least that isn't my intention. They are both clearly world class. But both have, in my view, little flaws that keep them from being absolutely on the top of the heap. Very close, tho.

Bishopwill, nothing is on the top of the heap. There are flaws in every speaker ever built. Each listener must decide how many flaws and which type can be tolerated on a consistent basis.

I agree with your comments about Avantgarde, but as for the comb filtering sound you mention concerning Soundlabs, you must have heard an early model.

Soundlabs now utilizes "Distributed Resonance" (their buzz word) , that eliminates membrane resonance and dipole energy cancellation. The diaphragm is sectioned where instead of comb filtering or resonant peaks, different sections of the diaphragm resonate at different frequencies in a graded fashion."

This essentially makes dozens of phase matched micro panels that are combined in the quarter circle radial pattern that Soundlab is famous for. The design is in fact, a giant electronic microphone in reverse. Much like the microphones used to record most of what we discuss in these forums.

If there were a cone speaker built that was phase accurate full bandwidth, and with as low distortion as Soundlabs, I would be interested in them. The (gross) dynamics of cone speakers are superior and that is their strength. The Soundlabs phase accuracy, speed and ultra low distortion is its strength.

What avantgards and every other good system needs to sound its best is a really good AC power supply. Often in many homes and businesses, several of the outlets are wired to the same one or two 15 or 20 amp breakers. These are used to power the entire system. Then, we try to add expensive power cords and conditioners to make the system sound better. A more effective way to great sound is to build a dedicated AC circuit to your sound room which is way beyond the typical household circuit. Lower resistance in the line by using larger gages, copper conductors, and less splices. Do this, and listen for yourself.