Audiophonics now has a NCx500 amplifier for roughly the same price as the Purifi.
AUDIOPHONICS HPA-S600NCX Power Amplifier Class D NCore NCx500 2x600W 4 Ohm - Audiophonics
The Audiophonics HPA-S600NCX dual mono power amplifier, an updated and improved version of the HPA-S600NC, is now equipped with Hypex NCore NCx500 amplifier modules. These provide twice the performance in terms of distortion and output impedancewww.audiophonics.fr
web site says "dual mono" which I always took to mean a dedicated power supply to each channel. This has one 1200W smps serving 2 modules, meaning they won't reach rated power.