I would like to write a csound instrument that just takes audio input, and
processes it to warm it up and roll of the highs a bit. Anyone have an
idea about what kinds of filters I would use? A low pass (tone) is not
going to do it, I think. I need to generally tilt down the response, but
6db/octave is way too much. I noticed that the parametric eq filter has a
shelf filter. That might help. Another idea is to make a very low q
resonant filter to warm up the mids and roll off toward the highs. Has
anyone done this before?

Hey, how about simulated tube distortion? :)

Mike