It's funny but all the responders are correct in their approach. My approach to solve the problem was to have a pair of passive devices made with a (RCA input and RCA output)plugged into the input of the power amp and my interconnect pluged into the device(s). One for R and L channel. This device rolled the speakers off in a controlled manner and you choose the frequency you want it to roll your speakers off. All that is needed is the input impeadance of your amp and what frequency you want your main speakers to roll off. When one of the responders spoke of distortion with the rolling off of the bass from your main speakers it frees the speaker up to produce clearer midrange, mid bass and top end frequencies with better dynamics too.
This can be done on solid state and tube amps but the device is custom to the amp you have it made for. Tom Tutay made mine for my Spica TC 50's and It works well for my TC60's too because they are rolling off around the same frequency. By it rolling off the bottom end of the satellite at say 40Hz the subwoofer takes over from there. Understand that rear ported speakers are harder to blend with a sub than front ported speakers. My subs are acoustic suspension and my TC60's are rear ported. After tinkering and placing them in various positions I have them blending pretty darn good. You have to play with the phasing. Oh, I have two Dali Suite 1.2 12" subs. They are not boomy and are pretty articulate. My TC 50's blend even better than my 60's and they are acoustic suspension. I still prefer the TC60's. This actually gives you more clairty, soundstaging, and depth of sound stage too from your main speakers thus allowing the sub to take over in the bottom range. This is one way to tackle the problem and it is effective. You can call Tom @ 850-244-3041 10am to 8pm CT.
This can be done on solid state and tube amps but the device is custom to the amp you have it made for. Tom Tutay made mine for my Spica TC 50's and It works well for my TC60's too because they are rolling off around the same frequency. By it rolling off the bottom end of the satellite at say 40Hz the subwoofer takes over from there. Understand that rear ported speakers are harder to blend with a sub than front ported speakers. My subs are acoustic suspension and my TC60's are rear ported. After tinkering and placing them in various positions I have them blending pretty darn good. You have to play with the phasing. Oh, I have two Dali Suite 1.2 12" subs. They are not boomy and are pretty articulate. My TC 50's blend even better than my 60's and they are acoustic suspension. I still prefer the TC60's. This actually gives you more clairty, soundstaging, and depth of sound stage too from your main speakers thus allowing the sub to take over in the bottom range. This is one way to tackle the problem and it is effective. You can call Tom @ 850-244-3041 10am to 8pm CT.