Pretty much all the pro-amps I've been exposed to, have fan noise. How much varies unit-unit as there are some production variances in the fans themselves, and when you tighten down the screws on the plastic housing, they make more/less noise. So... even if you could get a generic SPL reading from a fixed distance, in my experience, it wouldn't be representative of every one of the units that comes off the production line.
The Face Amps have about the same ambient noise levels as all the other pro-amps I've heard. So... if you need absolute silence, you need to plan for remote mounting. I can hear mine from 10-12ft during silent passages in the music.