Not really sure of this a problem or by design. When using a pure triangle wave, with no folder of other modifiers. The sound of a triangle wave though the Steiner filter only has a high frequency noise artifact with the filter wide open and LP mode. No resonance, brute factor is being used. When listening to the same triangle wave though the ladder filter wide open and LP mode, I hear a nice clean triangle wave.
So the question is, if this is a problem or not. And is there is anything that can be done. BTW, did a full calibration of the filters and no change.