I think these are quite a remarkable pair of speakers. Probably the most engaging pair of speakers I've heard for a while. I so glad that I finally built a pair.
I've had a little bit of time to compare then to the Specials in the living room. Whilst the IXs do sound much larger than their size, they don't quite size up to the Specials. The IXs certainly are wonderful, but I can push the Specials harder (probably just more air movement) before you can feel that they don't have anything more to give. The Specials do reach down lower. I'm sure that is just a direct reflection on the drivers' sizes. And I would say the Specials do scale better, surprisingly only just though, but are pretty much matched in terms of speed.
However, for simply being coherent with music the IXs excel, they have pose and grace and just spine tingling goodness. Just by the size of the driver's the Special have more growl and kick. It is impossible to have a winner, because they are radically different speakers, with different qualities, with the IXs having the coherent trait in spades.
I used NAP160, KSA50 clone and a Radford STA15 amps to compare the speakers...I do believe the KSA50 and Specials are a perfect match.
That all said, I think I would like to increase the HF output of the IXs. The 9300s in the Specials really shimmer and I feel the IXs need to reach a little bit higher. Atm I have two 18R, 5W MOX resistors in front of the tweeter. I was thinking of adding a 2W, 150R, MOX resistor in parallel, combining to about 8R5.
I've yet to do an AB with the IXs and Fortes, though I would not aim to replace the Fortes with the IXs, different horses for different courses.