Thanks for the replies.

To your points, my sub is set to auto on, but even though the light is green and the driver is vibrating it is not being driven enough to be audible. The insanely high level of input signal to "shock" the system into normal operation is far, far more than any auto on function would require. I have set the sub to always on and the symptom still persists.

I also use the 12v trigger on the SMS-1. It seems to turn on and off properly at least as far as the display panel is concerned. I have never used the night mode and have never had to adjust the SMS-1 settings in order to make it work properly. All it takes is increasing the input from the receiver until it works.

I did have one odd experience while running the bass sweeps. For some unexplained reason during the sweeps, I had a sudden dropoff of all bass response from about 40-50Hz and below. Then it started working properly again for an equally unknown reason. I don't know if this is related, but it would appear to me that losing all the lower frequencies would create all the symptoms I describe. Is there a known condition where the SMS-1 will lose the lower part of the signal from time to time???

I can leave the sub and the SMS-1 both in an always on condition, but I assure you that that cannot become a permanent condition. The SMS-1 must be able to be turned on and off with the rest of the system. I'll try these different connections and some different settings to see what works.