Well I think I have finally covered the SVS website cover to cover, its seriously interesting reading material. I stumbled on your calibrating subs section and had read the following >And finally, set your subwoofer amp’s volume control (if it has one) to at least half-way up to start. It’s a good idea to check the subwoofer level control of your receiver before you begin the test tones. Keep the receiver's subwoofer output control to about 25% up or lower than “0 dB” (or say -6dB given a typical receiver channel limits of –12 dB to +12 dB) . This will allow your amp to work with the cleanest signal possible from your receiver, while still leaving plenty of downward adjustment you can use from your viewing position (using the remote). According to my Yamaha manual and the S&V HT tune-up disk the directions were to set the receivers subwoofer output at the highest sub output and use the bass volume on the sub to adjust, on the yamaha that is 0dB. It ranges from -20dB to 0, so in your instructions in order to get the cleanest signal I would need to turn that to -15, or 1/4 up and then calibrate using the subs volume knob to around 80dB. I have not tried it this way but if it produces the best results I will give it a try. Also I have never heard a sub bottom out, what type of noise should I be looking for?