The cabinet construction is much different, in addition to the drivers. The Altair has perhaps the best cabinet construction in the industry which will equate to better settling times, a blacker background and more low level resolution. In effect, an Altair is half of an Arrakis. They are both point source speakers, so I would not be concerned putting either one in a moderately sized room. If you can handle the size in your room of the aquila, then you could also handle the Altair. The difference is not regarding the size of the room for either speaker, but simply better quality, more dynamic range, lower frequency extension and more resolution between the two speakers- exactly what it should be when spending more money.
