A friend just picked up a used M9 from GC. Great price at about $215 landed.
But it has a weird issue: When the Spring or '63 Spring reverb is first in the chain, there is a constant, unbearable crackling static noise. It doesn't matter if the effect is engaged or bypassed, or if the signal goes L-R or R-L. I believe I went through every effect, and there's no other problem with any other effect, including the rest of the reverbs, and only when in the first spot. Since it's unlikely that reverb would be first in the signal anyway, it wouldn't affect the useability, but he's probably returning it anyway. Any idea what would cause it?