Did some more investigating today. Per advise offered, I checked the loop on the Randall. I'm running a 31 band eq in it and I noticed that the send and return volumes were both maxed, so I backed them off to 1 o clock. Bumped the master on the eq slightly to compensate.
I also checked the power supply feeding my pedals. The junction where the wire meets the transformer was frayed and I could see copper. Replaced it with a new power supply. Ran the Randall through it's paces (with an X2N and a Metalzone) and it seemed to hold up just fine.
Warmed up the Picovalve and gave it a check and it seemed good too.
Hopefully it holds up. I think that the power supply was the primary issue and the fluctuation that I thought that I heard playing direct was due to the loop levels being maxed in the Randall. I'll put it down to ear fatigue playing direct into the Picovalve (no separate gain channel on that one).
So, as it's been said, so far, so good (and yes, so what).
Thanks to all for the assistance.
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