Bob
Where were the main culprit frequencies? This had to be more than a simple 20kz tone, right? And if so, could it have been interference from an external source?
I just did a test with the same audio setup, switching between the AGC “off” setting and the AGC “on” setting, rendered it out, and got no difference at all– and no noise at all. so now I’m wondering if it mat have been external. perhaps my low cost Chinese mixer is lacking in shielding some where?
Do you have a thought on it?