@smoge, fearing I may be heading off topic here…
atk-sc3’s Near-field Effect pseudo-UGens are built upon Ambisonic degree utilities, which are implemented as cascades of SOS and FOS UGens.
I have entertained the thought of putting together a simple separate quark that assembles the SOS (+ FOS) cascades from dictionaries of coefficients.
Other(?) additional quarks could provide the various recipes for higher order Butterworth (and other types of) filters, using this mechanism.