Quick starting point : Just MHO. Especially for movies and TV, you may want to set sub gain flat for music.
1. Set all speakers at same level with SPL ( I use 85 dB), the set sub hot by +3 dB to +10 dB ( 88 dB to 95 dB; again for music you might want it flat, i.e. 85 dB same as your other speakers).
2. Set front speakers to "small" ( this has nothing to do with the front speaker size, it activate the subwoofer crossover frequency). Make sure sub=yes
3. Make sure any crossover frequency on your sub is disabled (uppper cutoff set as high as it will go, e.g. 180 Hz); you will use AVR for crossover frequency
4. Set the AVR crossover frequency, a good starting place is 80Hz or 100 Hz; if your front speakers sound good at low frequencies you can set it even lower. Try a good movie with some deep bass and experiment.
5. If your sub sounds boomy, probably not with an SVS ..they are great. You can sub crawl. That is try moving he sub to diffferent palces in you listening room to get the best sound.
Good Luck ! ... AND ENJOY
MidCow2
P.S.- Relocated my sub to the back of my den last night in preparation for new audio TV furniture and new TV