Pipedream Crossover

You can contact Scaena, it's what pipedream evolved into.

http://mainframeaudio.com

Does anyone know if an electronic crossover can be used to
direct pre-amplifier low frequency output to a 'center channel' subwoofer
without without merging or otherwise impairing the signal frequencies above the lowpass crossover level ?
If the pre-amplifier L-R outputs are input separately to the crossover, the lowpass frequency is selected at the thresh-hold low frequency
capability of the 'full range' loudspeaker system, with steep rolloff,
the crossover lowpass outputs 'merged' to feed the subwoofer, and the remaining crossover outputs left unconnected, would the goal be accomplished?

Contact High Emotion Audio. They still make the Pipedreams and have updated crossovers for the older models.

Does anyone know if an electronic crossover can be used to
direct pre-amplifier low frequency output to a 'center channel' subwoofer
without without merging or otherwise impairing the signal frequencies above the lowpass crossover level ?

An electronic crossover can be used for this. Usually mono subwoofers have that sort of thing built in.