I have a pair of Paradigm studio 100's v.2 that I power with my Marantz sr-8000 recevier along with the cc and surround speakers. When listening to music I like to pull the bridges off the 100's and use them as a sub. I use the recevier's channel level control to turn up the left and right +10db and the bass is plenty loud. Ok so I bought this servo 550 stereo amp that has left and right channel level controls. I pluged it into the main preouts on my marantz and into the sub brackets on my studio 100's with my marantz powering the high and midrange. I thought I could then turn the Volume up on the subs with the servo 550 to have more bass. Well with the Channel Level controls at max on the servo it wasn't any louder but in fact a tiny bit quieter not to mention a louder hum when no sound is coming through. Now before you tell me to go and buy a sub (which I may end up doing if this dosen't work) I like the bass from the 100's it's plenty loud for my apartment and at the same time because they are 8's not to loud to disturb the neighbors too much. I want to be able to turn up the Volume on the subs independtly from the highs. Is it maybe that the knobs on the amp aren't Volume controls but Channel Level controls? Is there a difference?

Thanks -Mark