I only have the KAF 2 filter, and have never heard the DSP, but I am very happy with the KAF 2. If anything, position 2 boosts the cw signal, and I don't find any ringing on the cw note. I never use the KAF2 on SSB . I consider the KAF well worth the money, especially since I got it used at a good price. George, N4ym