At the 990, I have the sub @ +15 (no attenuation). I do this so that the sub gets a "turn-on" signal even at a low master volume. If I run the sub where the 990 auto-calibrated it, I have to turn the stereo up pretty loud for the sub to kick in. I use the sub's own volume knob to adjust its volume. Remember we talked about surround (digital) vs analog volumes being much different with the 990? No more startles; I jacked up all the auto-calibration channel volumes relative to each other, and that did the trick. The only thing keeping me from making all channels as if +15 were actual zero is the sub. I max out with the other speakers at 990 channel calibration +12 in order to get the [my] sub to turn itself on early enough.

The low pass cut-off frequency thing is new to me... Sometimes I see my sub has tuended itself off after three minutes of no (or too low of a) signal. Wow, interesting... it's not because of the master volume, it's because there is no sound information below 40 Hz. This just occured to me; last night I saw the sub off and cranked the master volume to some rediculous number like -1 db and the sub stayed off. Back to -25 db and later the sub came on by itself when the "spaceship" rumble occured. I hear the "night mode" works and it does have a bearing on the sub's auto on/off. I could probably use the 990's Max night-mode (min dynamic range) and set all speaker's relative volume level to the sub at the point the sub remains on continuous (with just a trickle). I'm thinking out loud, but that would work to set how loud the master volume is when the sub turns itself on... I might need some pink noise or brown noise for that. I do like the sub to come on with low overall volume because more base is good at low volume.

I don't know what you traded your 990 for, Gonk, but it must be sweet. I'm still trippin' every time I hear my new stereo... the only thing different is the 990. How can it sound like I have more powerful amps and speakers is a mystery to me. All I can say is don't skimp on a preamp, it can make a huge difference!