What is the most quiet return pumps?

[sphelps]

Originally Posted by BlueAbyss

Hmm, yeah I sorta thought so also, but it is a Tunze. And the synchronous drive probably makes it quieter than a regular asynchronous magnetic drive pump.

I would assume the quiet ones are also synchronous. Correct me if I'm wrong but I believe this simply means the frequency of the AC motor is consistent and therefore always turns at the same speed. This would likely be consistent with any magnetically driven pump. I'm fairly confident that these two pumps are identical, meaning the same motor and impeller.