While this is effective, it is not the best way to go about it. I suggest using a VSTi for your sub bass as you can have more control over its sound. waves r-bass and maxxbass are ok if done right. Is this the proper way to match a sub to say a reese? NO. And wot about those famous Tee Bee 'n Noisia basses? Do you really want an 808 sub sittin under those? I don't. They don't sound as natural as layering the sound 'n runnin a LP filter on it to get your sub then boosting that. Easily done in SX. Jus create a group channel, and route your synth or sample to that group channel. Then insert an EQ with freq cuts @ 30hz, and 90hz. This should give you a natural feelin sub.