I have a Quiet One 9000 - 2300 gph sitting on my garage floor neer used... Oh THAT'S RIGHT. Someone else on MAAST borrowed it 7 months ago, and never returned it!

If you can use a submersible pump, they are quite a bit quieter, as the water insulates the sound somewhat.

I have both Iwaki and GenX pumps, and both are fine, but not that quiet. Reasonably, but not THAT quiet.

If you have a choice, I'd go with 2 versus 1. Eventually, one will quit/fail, and at least you have another running while you get it fixed or replaced. In my 215, I had 2 closed loops with Iwaki/GenX 12-1300gph pumps, and a Quiet One 6000 (1700gph) return from the sump.