Overall Volume Question - Interface VS Mixer

I'm a returning Sonar user and have used Sonar for many years, took a few years off, and am just now re-learning the ropes of SPLAT (see I even picked up an acronym along the way). I think my question is pretty basic.
 
My previous set up was an MAudio 2496 PCI card and a Yamaha MG12 mixer with Event 5" Project Studio speakers and the Yamaha started to give up. Some channels only played left or right, not both, the volumes got flaky and it seemed to be tiring out after probably 10 years.
 
So I decided to give up the mixer and bought a Focusrite 6i6 to replace it. Overall the 6i6 is an adequate interface but I much preferred the hands on mixing options of the er.. mixer versus the FocusRite's software mixer MixControl. Also just added some new JBL LS305's (not much improvement over the previous Events but that's another thread)
 
That brings me to my question. With the Yamaha mixer I could turn up the volume and it would hurt, with people not even being able to stay in the room at higher volumes and I don't think I got anywhere near full volume- it was just too loud.
 
The 6i6 on the other hand has no where near the same volume levels and I was wondering if that was normal? I've checked all the system sound levels, the speakers are turned up all the way and they sound OK but just not loud loud like the mixer. The levels are fine and should be great for mixing but once and a while I want to crank things and the volume just isn't there.
 
I'm pretty sure there will be a couple of responses about not needing really high levels to mix or even to listen but that's not my question. Should one expect such a vast difference in volumes between a mixer and an audio interface? Or is there another place I could/should check for overall volume levels?
 
Thanks in advance.

Which Yamaha mixer? My reaction to the loudness question is yes, since that mixer is most likely also a PA with an amplifier section in it. The Focusrite is not an amplifier.

FWIW, I have a Yamaha mixer that emits enough EMI that I cannot use it to track condenser mics or sensitive guitar pickups.

brundlefly
Hmmm... seems it should not be a problem since the 6i6 "goes to eleven":
 
"Maximum Output Level (0 dBFS) +11 dBu, balanced"
 

 
But, seriously, my first guess would be a line level setting mismatch or maybe inappropriate cable wiring. Are you using XLR cables or balanced TRS?

Balanced TSR and from reading the reply above maybe the Yamaha (MG12) has another gain stage of sorts that the 6i6 doesn't have?

Soundwise
My 6i6 is not loud with my monitors either, so I think your set-up is fine.

Thanks for confirming that Soundwise, I appreciate the reply.