Sorry my post wasn't clear.
The setup I envision: cdp > pre > crossover > MC275 > speakers
.............................................................|_powered sub
The stereo amp would continue to drive the speakers (with their internal crossovers intact), but the amp would receive a signal from the crossover that would go down to...say 45Hz only. At the same time, out of the crossover would come out another signal, 45Hz and down only, that would drive the powered amp.
So it would be bi-amping in a way, as the sub is powered.
However I'm not talking about a crossover to replace what the speakers have in them.
The setup I envision: cdp > pre > crossover > MC275 > speakers
.............................................................|_powered sub
The stereo amp would continue to drive the speakers (with their internal crossovers intact), but the amp would receive a signal from the crossover that would go down to...say 45Hz only. At the same time, out of the crossover would come out another signal, 45Hz and down only, that would drive the powered amp.
So it would be bi-amping in a way, as the sub is powered.
However I'm not talking about a crossover to replace what the speakers have in them.