f32-flavoured prelude. param.read() resolves to f32
via FloatParamReadF32;
the audio buffer is f32 (the host wire format for nearly
every plugin format).
f64-flavoured prelude. The audio buffer is f64 end-to-end
(high-order biquads, oscillator phase accumulators,
long-running cumulative state where 24-bit f32 precision
shows up audibly). The format wrapper widens the host’s
audio buffer to f64 at the block boundary and narrows on
the way out.
Mixed-precision prelude (m for “mixed”). The audio buffer
stays at host wire precision (f32 - no wrapper-boundary
widening cost) but param.read() returns f64 so
intermediary math (filter coefficients, phase accumulators,
long-tail feedback) runs at f64 precision.