@jussi_laako I have picked this from “parallel” topic.
Can you tell us more about FIR2 ? what was your intended design idea for this ?
My current “SDM → SDM” setting is IIR+Xfi+7ECv2@256x48, this combination is fantastic (well, this you know), and I suppose it has formed a habbitual pattern. As I certainly tried FIR2, but to say “better” or “worse” I can currently not, to be frank, so rolled back to IIR. But after this remark of yours I’ve set it back to FIR2 to give another try, now with more curiosity.