As some of you may know, I am getting new goodies. See this thread
http://www.tomshardware.com/forum/246270-28-case-toys

I like my pc to be as quiet as possible. The sum total of my fan experience is the Thermaltake Silent wheel which says its dBA is 16 and an Apevia which says its dBA is 29.6

The Apevia are noisy, the silent wheels are, silent.

I just purchased (somewhat impulsively) 5 140mm Yate Loons which says its dBA is 29.6 (ISO certified)

Are they going to be as loud as the Apevias at same dBA? or does size matter?

I also have the Antec Tru Power Trio 650w with the fan controller. I have no clue how it works. Do the pins just under volt the fans which helps keep them quiet?

Thanks

depends really, if they are big they may spin slower if they are actively controlled but most like they will be louder thatn previous quiter fans

Yes, a decibel of sound will not change from one type of fan to another, it's constant.