• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Subwoofer connection?

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?