I used to have the exact same Q-Tron+ but I recently sold it as I came upon a killer deal on a Mu-Tron III. Anyway, when I first got it I had the exact same issue. Now I do not know exactly what pickups you are using or how you have your tone knobs set, but therein was my issue and solution.
My Strat currently has EMG DG-20 Active pickups in it. It is designed to look like a stock Fender Strat setup but the tone controls are completely different. Instead of having a master tone for the neck and middle pickups and the bridge wide open, EMG has what they call the EXG guitar expander and SPC presence control. The two knobs are an active EQ system that work in conjunction with each other in whichever setting you have the 5-way pickup selector switch set. So it's pretty versatile.
Check it out here if you are so inclined:
http://www.emgpickups.com/products/category/11/1Anyway, when I play I have the neck pickup engaged, the EXG on 7 and the SPC on 2 and it sounds great. Not Jerry, but that is soon to change. But my point is that while this setting sounds great for most anything I play, when I kicked on the Q-Tron+ (and now the Mu-Tron) the tone was kind of bassy, muddy, lifeless. However, when I switch to the middle pickup and set both "tone" knobs to about 6 - total Mu-Tron funkout!!!
Keep your gain on the Q-Tron+ down (so on your loudest chord/note the red light comes on), the peak around 12 noon, and try out some different pickup and tone knob settings. You'll find the sweet spot on your guitar for that effect and end up right where you want to be.
Happy hunting (and funking)!