What you propose will not work properly because the Vandersteen subwoofer design is unique. The Vandersteen x-over is simply a capacitor in line with the preamp which rolls off the lows to the amplifier (main speakers) at 6db per octave. The hinge frequency is determined by the value of the capacitor and the input impedance of the amplifier. The Vandersteen subwoofer adds a 6db bass boost to the signal it receives (via taps to the main amplifier) to compensate for the roll off. Other subs use the line from the preamp as input. They then employ a crossover with outputs to the main amp. This takes the bass load off the main speakers. The advantage of the Vandersteen approach is that the signal to the main speakers avoids switches, op amps, inductors, and what not in the signal path, not to mention phase problems inherent with steep slope x-over designs. FWIW, when one uses the Vandersteen subwoofer, it is a good investment to buy the very best capacitors available (MIT,Hovland, etc.), and install them at the input of the main power amp(s).
Vandersteen high-pass filter with other Subs
I would like to relieve the midrange congestion of my Vandersteens by inserting a sub(s) with high-pass filter, per Vandersteen's own design.
I already own REL Stadium III subs and would like to keep them. Would there be any problem inserting a vandersteen x-over between my pre and amp (say, e.g. the one used in the model 5) and sending the outputs of my amp to the RELS, rather than to Vandersteen 2WQs? Or will I have some sort of impedance or other circuitry issue, of which I am currently happily ignorant?
I already own REL Stadium III subs and would like to keep them. Would there be any problem inserting a vandersteen x-over between my pre and amp (say, e.g. the one used in the model 5) and sending the outputs of my amp to the RELS, rather than to Vandersteen 2WQs? Or will I have some sort of impedance or other circuitry issue, of which I am currently happily ignorant?