As an experiment I put a volume boost in front of my Hartke lh1000 head. My hope was that it would drive the tube and give me a little bit of tubey grit. I used an MXR 10 band eq for the volume boost. I tried it in both the active and passive inputs. The result was a pretty lame farty sounding distortion. Kind of like a speaker being pushed too hard. As would be expected the distortion was more pronounced when boosting the passive input.