I have no idea what or why you are getting noise, I have never had any situation with any of my RLC-1, anywhere in any system, there must be a way to avoid it.
Previously, how was your vinyl set up? Re-create that, Chase out, still noise free?
IOW, perhaps moving something, something else happened, another connection got moved .....
Out of nowhere, I used to get problems that turned out to be the very worn and slightly undersized rca jacks of my McIntosh MX110z tube tuner/preamp. I’d work on the CD cables, and the tape player’s cable at the other end would be moved inadvertently. That’s when I changed to Locking RCA connectors,
When Audio Classics went over it, they routinely changed all the MX110z’s RCA jack panels to new gold plated ones, so glad they did.
There is no reason not to use it for normal or higher volumes, still get it's remote features: once it gets back up to it's default volume or higher, no signal modification is happening.
And, the two sets of rca outputs 'front' and 'rear' are identical, it is from the weird days of early quad, no processing, where they just put 4 speakers in a room with a front/rear fader.

