I had two NAD Purfi units in my house and neither stayed long.
Ran hot, glitchy and hardware issues.
Modern Class D amps like those from Hypex or ICEpower (used in many high end brands) are simply excellent performers, musical ruler flat frequency response, SN numbers that other amps can only dream of achieving and they are respectful of power use and efficiency.
Heat and thermal cutoff is the real issue, as the power supplies can get excessively hot. Attaching finned heat sinks (ones with adhesive attach easily to flat heat shields) and providing sufficient air flow is crucial. Plus running hot kills performance. I've found AC Infinity fans with a Controller and a sensor work well and the speed is adjusted according to temperature. When the sound is not turned up the fans will be slow or stopped.