I've owned a Crown 2k XLS class D for a couple of years (roughly) and I've never had the inbuilt fan cut in yet, not that I've noticed. As other posters have said, valve amps tend not to have fans - I've had Marshall (plexi), Ormat & Matamp, none of which had blowers, nor needed them (though the big Ormats did get a bit warm towards the end of the night).I recently had my tech replace the jump-jet fan on my Marshall twin100 chassis with three slower, quieter (& more efficient) units.........you pays yer money..........