I've had my S-400-12 supply since March when I got my TS-450SAT. Yes, it was overkill, but I figured I'd better leave some room to grow. I'd just gotten my license in January, and was told this hobby apparently has a way of breeding radios when you're not looking. (Sure enough, there's a TM-721A now setting on top of the HF rig.)
While the small fan inside isn't noisy by some comparisons, I, too, wished it was quieter. Rather than build a box, I exchanged emails with John asking about CFM requirements, etc. for a fan swap, and received a quick reply each time... and on a Sunday, no less. Fast forward to today. I had another (final) question about current draw on the fan circuit, got another almost immediate reply from John (OK, it took a whole
six minutes), and proceeded to complete my "bigger fan, lower speed, more airflow" installation. Now the fan is virtually silent, and cooling will be as good or better than with the OEM one.
Kudos and thanks to John and MegaWatt for building a quality, US-made product at an affordable price, backed with great customer service and support.
KE0PSJ