Pedal Order and Noise

[squirrels]

I'm not sure is this is more of a debugging question but I just built a Doomidrive and I've noticed that when I place it towards the end of my signal chain it whines when the pots are dimed but when early or alone it's fine. I've never really noticed this before in any other pedal. Buffers didn't help. Is it an impedance thing or something else?