I can't answer Q1, but for Q2, did you want to drive the sub using high level or low level inputs? High level depends a lot on the sub you get I think. If you use low level you simply connect the sub to the preamp outs on your Cary.
Have you considered using the Dahlquist sub and xover? With that vintage setup, I would be very tempted to go that way.
Have you considered using the Dahlquist sub and xover? With that vintage setup, I would be very tempted to go that way.