I don't know if I'm in the right place but here goes. I have a 990/7075 setup with Orb audio Mod2s (7.1). Iam getting a screech through the speakers when audio formats change from program to program or program to commercial when watch TV. What could be making this happen. It doesn't happen in any other instance. Any help or suggestions would be greatly appreciated. I'm racking my brains here. Thanks in advance.

It sounds like an issue with the 990 identifying the incoming audio format. Does it happen with any other sources (such as DVD's at the start of a movie or when entering the disc menu)? What cable box do you have?

No it only happens with television play. I have Direct TV Box H21-200

HD broadcasts can be either Dolby 2.0 or Dolby 5.1, and the HD receiver may also output PCM in some cases (don't use satellite, so I don't know how likely that will be). The format will change between programs (either on the same channel or different channels), and it also often changes for commercials (which are less likely to be in 5.1). The 990 needs to be able to determine what the incoming audio format is before it can properly decode it. For some reason, the DirecTV box is giving the 990 some problems, and it is briefly decoding using the wrong format (creating the screech).

There are two things that you might try. One is to switch digital inputs, since the H21 has both optical and coaxial. It shouldn't make a difference, but there's something peculiar happening with the H21 and it's worth at least trying. Another is to change the audio output setting on the H21. On page 51 of the manual , you can see three tabs under the "Audio" settings. The third is labeled "Dolby Digital" and it will likely offer options for Dolby Digital or PCM. Dolby Digital is preferable, of course, as it lets you play 5.1 sources directly. If it is set to PCM, then I suspect the box is briefly outputting DD and then changing to PCM, thus confusing the 990. If it is set to Dolby Digital, then there's something odd going on with how the H21 outputs the bitstream and you might try changing to PCM to see if the problem persists.

Thanks for the help Gonk. I changed from optical to coaxial and voilà, no screech. I also changed from PCM to Dolby Digital. Anyway, no more screech. Been bugging me for months. Thanks again.