hey hey,
Just like a normal eq. on a mixer the less u add positive gain the better, eq should b as much as possible flat (except when changing over tracks or if u are adding a particular set of sounds freq.s from one sorce 2 another, ex.. a synth line/ vocal from a record 2 another record providing the rhythm)... so if possible just use the channel's gain 2 do the compensation so nor the channel input reds out nor the master out!
Normaly if u add 3db with eq and then cut the master level U'll have basically the same output as b4 the eq'ing BUT u'll b possibly adding some distortion on the channel or just by using positive gain (most of times this just sound louder and not necessarily sweeter!)...
my 2 cents,
Z