2.1 system / help needed

[newpaton]

Ok,

I am setting up my 2.1 system using modified tangband w3 881s in an aluminum/concrete 2 liter tear drop shaped speaker and subwoofer crossing over at 120hz. The enclosure is sealed giving me a 12 db octave slope at around 120hz and since I will be using a Sonic Impact t-amp with modified input cap of around .06uf I will get another 6db highpass. The problem is dividing the signal so I can send a summed mono signal to the subwoofer (mirage nano). A search resulted in the following schematic. Does this seem ok?

http://www.rane.com/pdf/ranenotes/Why%20Not%20Wye.pdf

Probably i will take the signal from cd player, into preamp then divide it into two (using rca dividing jack) and send one stereo signal to the sonic impact and the other to the circuit as described above and then to the sub.

Does this seem ok? or is there a better way. Any help is appreciated.