Using the Radioshack SPL meter, I ended up turning my SVS 25-31 sub volume level to slightly past the one-quarter mark, with the AVR channel level set to 0. Is that similar to the experience of other SVS users here? The SVS guide says to start with the sub turned up to 1/2 or 3/4 on the volume level. I thought it was odd I had to reduce it so much. (I used Avia). Also, if I set my full-range main speakers to work with the sub ('sub plus L+R' on my HK setup), do I measure sub output with the main speakers off or on? Naturally, I get different readings depending on how I do it. I even have to turn the volume level lower on the SVS -- below the 1/4 point -- when I measure with the mains on. I also find that output is vastly different when I compare the sub individually to the Left and right main speakers. I guess that's no surprise The left speaker is in a right-angle corner. The right speaker's back port empties partially into a more open part of the room that leads to a narrow hallway.