So... have any other 990 owners tried doing this? I mean, feeding a white noise signal to an analog input, and toggling between the various modes? Incidentally, to give you an idea of what comb-filtering sounds like...if you put a cardboard tube up to your ear...you're hearing comb-filtering. Mind you, the nature of the comb filtering depends upon the length of the tube, but you get the idea.

Finally, it was easy for me to discern the difference between the sigital input version and the analog input version (of the same signal). Lastly, if you do not have a white noise .wav file (or high bit-rate mp3), you could use the sound of ocean waves as a surrogate test signal, or email me and I'll provide a white noise signal to you for use (though there are test CDs out there that feature white noise...I'm sure).

Thanks,

Mark