Test Files Just Added:

On the FTP site mentioned above, I just added six files than can be used for diagnostics (for helping to identify this issue or for other things). You will find them in the folder test_files.

NOTE: I assume no responsibility for how these files are used. As with any test, if indeed you are going to use these files, always start with the gain (volume control) all the way down on the 990 (or other device) and GRADUALLY increase the gain (volume) once you know the file is playing.

The files are:

1) White Noise, 20 Hz - 20 kHz, 2-channel, 300 seconds' duration (.wav, 44.1 kHz, 16-bit)
2) Pink Noise, 20 Hz - 20 kHz, 2-channel, 300 seconds' duration (.wav, 44.1 kHz, 16-bit)

From these two files above, the following four files were derived:

3) White Noise, 20 Hz - 20 kHz, 2-channel, 300 seconds' duration (.flac)
4) Pink Noise, 20 Hz - 20 kHz, 2-channel, 300 seconds' duration (.flac)
5) White Noise, 20 Hz - 20 kHz, 2-channel, 300 seconds' duration (.mp3, 320 kbps)
6) Pink Noise, 20 Hz - 20 kHz, 2-channel, 300 seconds' duration (.mp3, 320 kbps)

Feel free to use these for your own use.

If you want to try and replicate what I did (in order to see if your 990 exhibits the same problem) then burn a CD with these tracks and connect your CD/DVD player's analog outputs to an analog input on your 990. I would suggest that you use the white noise file rather than the pink noise version simply because there is more high frequency energy present in that than the pink noise version.

If you have an mp3 player handy, copy whatever format you prefer to use (.wav, .flac, or .mp3) and use a 1/8" to RCA male adapter cable and plug that into an analog input.

If your 990 exhibits the same problem as does mine, you will hear it right away when the analog source (to which your CD player or mp3 player is connected) is selected. Cycle through the various modes (STEREO, BYPASS, UPSAMPLE, DOLBY, DTS etc) and listen.

If you have a zone 2 feed, my guess is that you will not hear the comb-filtering in zone 2 - at least this is what's happening in mine.

Mark