Intergrating a powered sub..Question

Yes, the KG5230 plate amp has a volume knob. Which CDP do you have? Have you tried contacting the manufacturer?

Wait a minute, I'm a bit confused. You're using a Cayin integrated right? Now which do you have, the Rotel amp with Marchand crossover or a subwoofer using the KG5230 plate amp?

You shouldn't need another preamp since either the Marchand such as the XM9 or KG5230 with their crossovers and volume control would function as such.

If the Cayin has a preamp out you should be able to run that to the Marchand then from there to your sub amp. Or if you're using a KG5230 plate amp, that will have a crossover, volume control and amplifier all together. So in effect, the Marchand and your KG5230 are both preamps/crossovers.

Form there hook the sub to either the speaker outs from your Rotel amp or the KG5230.

Actually, you may not want a volume control on the pre out from your Jadis. Is this a preamp or integrated? It's best if you eliminate cascading volume controls and crossovers along a single signal path. Let the crossover control the volume. The only possible problem that might pop up is if the output impedance of the integrated and input impedance of your subwoofer amp aren't well matched. I experienced this once with an Electrocompaniet ECI-3 integrated and NHT SA-3 sub amp. No matter how I adjusted the volume , crossover or phase settings on the NHT amp, I couldn't get it to sound right with the ECI-3. This isn't very common though.

Choosing which sub to build and what size driver to use depends a lot on the what you want it to accomplish and the size of your room. For music I definitely wouldn't go too big. No more than say 10" in a small room and 12" in a medium sized room. If the driver is too large you'll sacrifice speed and detail, and it may be more difficult to integrate with your main speakers as a large sub trying to keep pace with small, fast speakers won't synch well.