What modes are you switching between?
I'm switching between stereo and surround modes. For instance, if I switch from 5-channel stereo to 5-channel surround, I will lose the center and sub. Also, I can switch between various stereo channels and subsequently lose the signal when I go back to 5-channel stereo.
I called B&K and was advised to reset the processor which I did, but that didn't solve the problem. It appears worse now. I haven't been able to get anything from the center or sub all day. Usually I could just switch the system off and regain those channels, but now that doesn't appear to work.
You likely have a speaker configuration setup that allows for different configurations. You need to tell the DSP what speakers you have setup for each mode.
Surround will often have a different set of speakers associated with it than Stereo/Music configuration - most DSP's handle this.
Furthermore...if you are listening to an analog source then the only way to get Center and Sub info is to digitize the signal ....this means you may have to select the appropriate SIGNAL PATH. Many DSP's support configurable flow paths for each input (Analog direct or Analog to Digital...in the case you have a CD player hooked up with both Analog cables and Toslink digital cable). Only the digital data will allow the DSP to do its stuff and create center channel or sub info from an original Analog Stereo signal....and you can only get DIGITAL by DIGITIZING the Analog signal or selecting the CD Digital In flow path on the input of the DSP!