I found a set of RCA shorting plugs. I turned everything off except for one mono block, inserted the RCA shorting plug, and the noise is still present.
I tried a different power cord, and the noise is still present.
I tried an XLR cable between my power amp and preamp, the noise is still present.
I have ferrite beads (made of material 61) on order.
I tried a different power cord, and the noise is still present.
I tried an XLR cable between my power amp and preamp, the noise is still present.
I have ferrite beads (made of material 61) on order.