Yes, this is a problem. If you put +4 into the line inputs it comes out as -10 in Pro Tools. That's waaaaay too hot. I'm not sure what they had in mind here. Even if you are using a console insert point that runs at -2, you still hit PT at -16 which is a little too hot for my tastes. I built up two 8 dB resistive pads in barrels to use with the line inputs.
No, the front panel faders do not control the line input gains.
Related notes:
This is
not a problem at all with the Eleven rack....+4 in gives -18 in PT just like it should be.
Also with the Mbox 3 pro & Mbox 3, the microphone inputs are just the opposite....they are low in gain. See
http://duc.avid.com/showthread.php?t=319700
btw, I packaged an old API 312 card onto a 500 rack panel & edge connector. I run it into the line input of the mbox 3 pro. I only use one of the secondary windings in this case & it works extremely well. IMO you should be able to obtain excellent results with what you have when you get the level issues straightened out.