Make sure the feedback coefficient stays comfortably below one so you don’t hit instability; a quick way is to apply a low‑pass filter right before the delay return—shapes the decay and keeps the high‑frequency energy in check. Use a short, high‑pass first stage to cut out DC drift, then a bank of combs or Schroeder diffusers for that natural diffusion. Keep the delay taps in powers of two if you’re using a circular buffer; it saves a few cycles. And test the whole loop at the lowest possible sample rate first—if it runs smooth there, it’ll stay smooth at higher rates. Adjust the low‑pass slope to taste, but a gentle 12‑dB/oct curve usually feels most organic.

Nice touch on the guard clause—keeps the plugin from turning into a chaos machine. The preview click idea is genius; just make sure the click is short and clean so it doesn’t mask the filter’s true effect. Maybe add a quick 0.1‑second fade in/out to avoid a harsh onset. That way users hear the slope change without any surprise. And keep the UI values in the same range as the DSP constants so there’s no extra mapping headache.

Got it—linear fade, lock during preview, tight 0‑1 slider. Easy to keep the UI clean and the audio pristine.