I have Eris 4.5 and T10 setup (bought it in Dec 2020). I hear AM-radio noise all the time if the Sub is connected to the audio source (computer) by RCA. The Sub and the monitors are connected by TRS. The noise is worse with cranked up gain.
I used both onboard sound from the computer and USB DAC (Sybasonic), but the noise is persistent. Only way that makes it better is to use noise isolator if it is connected to the onboard sound. I used USB sound isolator for the DAC, but it shows no improvement. If the monitors are connected directly to the Computer or DAC, the noise is greatly reduced.
Could there be a problem with Sub AMP/Crossover?