Just wanted to expand a little on Jim's good comments based on my own experience with the stuido EQ ...

The Studio EQ is neutral, for the most part at least! I think it is completely neutral only if your input signal level to the Studio EQ is less than about -9dB at 0dB or negative gain settings. In many use cases you may have a higher input level if the Studio EQ is placed after the amp or mixer.

After running into distortion problems I checked a whole set of data points via USB and a DAW and found that just placing the Studio EQ into the signal path lowers the output signal by an increasing amount (up to about 2dB) even when its gain knob is left at 0dB if your input level is above -9dB. Also watch out for incorrect dial knob value to output level translation. What you dial in may be up to -2dB off from what you'd expect to get even if you output is less than -9dB.

Within this 'margin of error' your dialed in gain only does what you expect if the adjusted output level is below -9dB. If your gain setting tries to push the output higher the studio EQ starts to 'soft clip' (initially very little) and gives you even less output level than you'd expect from the gain setting (and factoring in the error margin). Depending on where you started and how much gain you dial in you can get quite nasty sounding ouput distortion. Note, it does all that well below 0dB, the reall digital clipping point.

I believe the Studio EQ behaves like this because Line 6's model imitates the real API 550b, which has a soft clipping feature and 12 or more dB headroom, i.e., you'd need do start this 'feature' imitation that many dB below 0dBFS as there simply is no way to do 'soft clipping' above 0dBFS. My guess that 'feature' kicks in at right about -10 to -9 dB input level.

Hope this helps some Studo EQ users. I'd guess most of us have run into some unexplained distortion with it. I can post my data in tables should anyone be interrested in the details. Let me know (and give me a couple days ;-).

Martin