ProAc is an English loudspeaker manufacturer that doesn't change models willy-nilly: if it works well and people buy it, then why change it? And if change comes, it should be purely evolutionary, perhaps a refinement of the crossover, or drive units replaced by improved versions of the same models.

So, for ProAc, replacing the popular Response D38 with the D40 ($12,000/pair) represents change that is near-revolutionary. Rather than the polypropylene bass/midrange drivers used in the D38, the D40 uses drivers with carbon-fiber cones, very light but rigid. The tweeter is now a ribbon rather than a soft-dome unit. And the D40s sounded excellent, in a system featuring Simaudio's new Moon 850P two-box preamp, Moon 880M monoblock amps, Wadia four-box CD player, and XLO cables. The speaker looks great, too, especially in the ebony finish of the demo speakers ($1500 extra).