What is the best way to hook up a subwoofer

The answer will depend on what kinds of inputs the particular sub provides. What make and model is it?

Regards,
-- Al

Pdspecl and Bruce (Bifwynne), I had looked at several pictures of the rear panel of the SP9, including at ARCDB.WS, and they show only one pair of main outs (plus two pairs of tape outs).

Excellent comments otherwise, Bruce. I would just add that according to the specs shown in Stereophile's review, while a load capacitance of 100pf (or less) is recommended, up to 1000pf is acceptable. That would seem to make sense given the 250 ohm nominal output impedance, and might particularly be a significant fact if a y-adapter turns out to be the best approach.

Best regards,
-- Al

Bruce, I'd feel pretty certain that the tape outputs are not volume-controlled by the preamp, and therefore can't be used. If the sub doesn't provide speaker-level inputs, using y-adapters with the single pair of main out jacks would be fine, IMO, provided that three criteria are met:

1)The sub provides separate line-level inputs for the two channels, not just one input jack that is intended to receive a summed mono signal.

2)The paralleled input impedance of the sub and the main power amp is at least 20K, as you indicated.

3)The total capacitance of the cables to the sub and the main power amp is less than 1000 pf.

If the sub provides high passed line-level outputs, connecting it between the preamp and the main power amp would be another possibility to consider.

Best regards,
-- Al