I think you mean no stereo buss compression. -18db is 0 in the analog world.[/quote]
maybe this will help ya see what i'm saying

(a master fader example in ableton live.. whatever your recording into you have one)
im assuming your tracking into a daw
when making your mix that you will render or bounce out ( 2 track stereo .wav file) that will be the actual file sent to mastering engineer or mastered yourself later.
don't apply a compressor/limiter to the master fader ( mastering will pump it up)
have it peaking at or just under where the meter is peaking in the pic above[/quote]
The "master fader" is the stereo buss.
What I was correcting is the fact that the stems of your song can and should be mixed (ie filter, eq, comp, fx) but yes the "master fader" or stereo buss should not be limited or compressed.
I am not sure what the OP intended now by the responses. Are we talking about what level your monitors are calibrated to mix? (ie 83-85db, tested with pink noise and an SPL meter.) Or what level are you printing your tracks? (ie RMS, peak value.)