Subwoofer connection?

[Skorpio]

I will try to test a subwoofer in my stereo set-up. The question is how to connect it...

The source is a Squeezebox SB3 feeding a DAC via S/PDIF coax, then a common cathode amplifier with 12BH7A feeding a F4 power buffer...

I am considering to options:

1. Adding a "sub output" to the tube stage. Connect two 10k resistors from each output capacitor to a commen RCA terminal and then terminate this point to ground via 100K resistor.

2. Taking the subwoofer signal from the analog output from the Squeezebox

Option one will need some rework in the amp and perhaps degrade sound, by loading the circuit?

Option two might have some timing problems? Are the two signals identical in time?

 

[DF96]

You can't assume that two different DACs take the same time to produce and filter a signal. However, for low frequencies this might not matter as the timing difference is likely to be just a small fraction of a cycle. Try it.