This is not the first CD to offer such a programme in recent years, but whether 70 minutes-worth of undiluted isorhythm makes for great programming is debatable. As though acknowledging the point, Cantica Symphonia interleave a few non-isorhythmic sacred pieces within the selection (which is in any case not quite complete). Like the Huelgas Ensemble (who offer a complete selection – Harmonia Mundi, 11/00), they opt for both voices and instruments. From a sonic point of view this works well, apart from the jarring irruption of the crumhorns in Nuper rosarum. The singers are more than able to cope with Dufay’s occasionally fierce demands. How well they sound on their own can be gauged from the Salve regina.

Those familiar with the Huelgas recording will be aware that there is no chopping and changing between voices and instruments, as is Cantica Symphonia’s constant habit. There is, I know, a tradition of performing the music this way but, try as I might, I cannot understand the need for it here. Apart from its arbitrariness, the ploy occasionally misfires, as in Ecclesie militantis, when a line appears to drop out entirely, such is the contrast between voices and the single string instruments that temporarily replace them.

It seems a shame, especially given the vocal quality, that the direction could not have been crisper. For the Huelgas, Paul van Nevel plays it marginally safer but it seems to me that the best way to approach this repertory still involves picking and choosing from several of many mixed anthologies. I rather suspect that the same goes for the programme, too: there’s no ‘one-stop shop’ for Dufay’s isorhythmic motets; at least not yet.