fn synth_channel(&mut self, chno: usize, dst: &mut [f32]) {
let coeffs = &mut self.coeffs[chno];
let delay = &mut self.delay[chno];
fn synth_channel(&mut self, chno: usize, dst: &mut [f32]) {
let coeffs = &mut self.coeffs[chno];
let delay = &mut self.delay[chno];