most accurate loudspeakers....

Many of you are correct, it is personal choice and your own ears. Now that being said ,I do agree with Stevecham in that Thiels are incredibly accurate and one of the best
loudspeakers I ever heard was a Thiel CS 7.2 my ears that is.
Gregm- I have my doubts. The only independent measurements I have ever seen of an ATC speaker were not very impressive. On the contrary. The distortion levels of their dome midrange was completely unacceptable (Stereo Sound issue 155).
I must say, that to my ears, that is how they sound as well. Especially when driven hard. They get harsh and glossy sounding as soon as you push them.

I have not seen the plots you refer to so perhaps you could PM it? Your observation that ATC powerful mid domes can sound harsh when driven hard is a fair one. ATC claim IM distortion in the inner ear affects hearing at extreme levels (could it all be marketing hype as you suggest - I don't know). What I do know is that they sound too harsh on certain recordings like Green Day and other hyper compressed modern CD's (ONLY when played extremely loud of course). Bear in mind, that it is principally the dispersion pattern of a dome mid which is desirable and not low distortion levels. It is well known that large dome mids are difficult to build with distortion levels as low as regular cones - ATC actually uses two suspensions to help maintain VC alignment.

So playing loud while maintaining accuracy/linearity similar to what can be achieved quite easily at low level, as you point out, is extremely difficult to achieve (exponentially difficult in fact). This is why most cheap headphones are very impressive in linearity and distortion figures compared to speakers! This is why there are a great many excellent speakers that go up to 100 db SPL.

Incidently, your Magico's apparently use constrained layer damping in the mid range cone. I read somewhere that ATC is doing this too on their entry line...lighter cones, smaller motors and yet well damped...a recipe for good sound to me! I must admit the Magico V3 sure looks impressive and the Ultimate is so extreme I doubt I'll ever see one let alone hear one! You could do us a favor and post pics of your Virtual System as I bet it is accurate ;-)
Seems to me that if someone has come up with the "most accurate" or "least inaccurate" speaker that all would follow and we would have one universal speaker. The truth is IMHO that the degree of accuracy or inaccuracy is measured - after all is said and done - by the ear. For every criticism there is a positive review somewhere. How could we ever find common ground on this issue - unless you choose Maggies!! LOL
Shadorne - Thoughtful reply. Thanks. I think that it is difficult to keep IMD down with any “soft” dome. You are practically operating in a non-pistonic way. Not ideal for “moving air”. Yes the dispersion of a dome mid is very nice but it takes more to tango. The MAGICO’s do use an incredibly stiff, yet well damped, cones. The dealer had a cone on hand to demonstrate how he can stand on an 8 grams 6” cone and not break or bent it. Very impressive. I have notice how easily you can push the V3 to dangerous SPL without realizing it. Clear sign of low distortions. I got to watch out, my wife claims I am losing my hearing… One of these days I will post my system up. It is always too messy to photograph. Not too fancy but I think that if nothing else, linear with very low levels of distortion.
There is an old comparison of ATC-300 and Dunlavy something here. If I were to stress the point, I would agree that there is some irregularity at the upper mid region at high spls; maybe that unit is somewhat stretched, or the cross to the tweet becomes iffy at very high voltages that don't seem to affect the woofs in the same way.