I haven't used the Saffire interfaces, but the Scarlett 18i20 I have is very quiet going into my Equator monitors.  I would think the noise you're getting is not the norm.

Thanks for the confirmation, aspenleaf. I believe the only difference between the 18i20 and the Pro 40 is USB versus Firewire.

One thing you could try is get a loop-back cable and run RMAA on it. See what kind of noise it has going straight from its outputs back to its inputs. If it is high, then you know you probably have an issue in the card. If it is low, then the issue is probably something else.

For a simple comparison my 6i6 reads as -95dB noise from main outs to front inputs, main volume all the way up, front inputs set to bring the level to -1dB, running in MME mode (RMAA was fussy about ASIO). While I don't have my speakers wired to the analogue out, that should end up being totally silent as room noise would be way above that level, even for loud speakers. The noise level reported by RMAA is going to be the total noise of your inputs and your outputs combined.
 
Oh also, since I had to use MME, looks like it was all 16-bit mode anyhow so maybe they are actually even less noisy. For whatever reason RMAA won't do the test in ASIO mode on it so I can't try that.
 
Either way, see what you get.

I've got two Scarlett's , an 8i6 and the 2i4. When I saw this I thought to myself, have my units been hissing this hole time and I was to oblivious to notice. I turned them both up to a pretty hi volume last night. No hiss.

The noise is completely independent of settings on the interface. It is constant even with the interface's main volume control and all input gains all the way down. It is there even with the Mute button pushed in. The noise is definitely originating in the interface, because it stops when I unplug the speaker cable.
 
I have not made an actual measurement yet, though. I'll do that today. I'm wondering if my expectations are just unrealistic. I'm accustomed to no perceptible noise, but perhaps the MOTU was just very quiet.
 
Part of the problem, I think, is that I've always felt the gain was too high on my ADAMs. With both the current and previous interfaces I've had to turn the output down to -30 dB. So another question for Focusrite users, please: what do you have your main volume set to? (Your speaker type and whether or not you're K-system calibrated would be helpful information, too.)
 
 

I remember monitoring around 12 Oclock on the dial (straight up) about 50%. 

Hi Bitflipper,
 
It sounds like you may need to engage the active monitor pad setting in the Settings menu of MixControl.  This should take care of the noise floor you are hearing with your ADAMs.
 
If you continue to have abnormally high noise floor issues, please get in touch with our support team via this link:
 
http://us.focusrite.com/answerbase/contact

With my monitors set to -10dbV, and a -20db pink noise signal inserted into a track in Sonar, and the track fader and main bus fader at 0db, to get an 80 db SPL (C weighted) at 36" from the monitors, my main volume on the Scarlett is at -8 db in Mix Control.

With the K-14 calibration, the main volume in Mix Control is it -13 db to get 80 db SPL (C weighted) at 36", in a treated room, with Equator D5 monitors.