Luxman L509X owners - Question about Main In


Hey there...

I own a 509X that I bought used back in August '18. I recently picked up an Anthem AVM 60 and I'm running the main pre-outs into the RCA "Main In" (HT bypass) to run left/right on home theater. However I am noticing a faint 60 cycle hum from the mains (very sensitive La Scala IIs). I do not hear any noise at all from the other speakers in the HT system, which are running from a Monolith 7X amp. 

If I hit the "Separate" button on the 509X (using the internal pre) the hum is not there - it is ONLY on the Main In when the "Separate" button is engaged. When I plug the same Anthem pre-outs into the Line In input of the Luxman, there is no hum.

My worry is that this is an amp issue with the Main In input/preamp bypass function, as I can't replicate it in any other inputs. Is it possible there is an issue with the Main In/bypass input? I hate to have to send the whole thing off to be looked at, and in theory I could bypass the 509X for HT altogether and just run my mains from the Monolith (will have to add another 2 channel amp for Atmos speakers). But I'd like to know if there's an issue with my Luxman.

Thanks!
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Thanks for the feedback... It does appear to have gotten worse the more I pushed things around back there. Now it is audible when watching a normal TV show, etc in the background. 

@dpac996 , Are you saying run from the preout on the 509X directly into the Main In, like a loop? So like play music from the DAC plugged into BAL 1, run a plug from PRE-OUT to the MAIN IN jacks right next to it? Will that damage anything, or at the very least tear a hole in space and time?

@erik_squires there is no coax in my system unfortunately, just a whole bunch of DACs, amps, Apple TVs, Orbi satellites, Hue Bridges, and the like. It is quite a mess behind my BDI cabinet but it seems like I may have to start from scratch today unplugging things to get the bottom of things.

@ricred1 - so just run a wire from the thumb screw on the AVM 60 to the screw on the 509X? I will try that too, thanks!

Anyone have experience with the Emotiva CMX-2?
@dpac996 , Are you saying run from the preout on the 509X directly into the Main In, like a loop? So like play music from the DAC plugged into BAL 1, run a plug from PRE-OUT to the MAIN IN jacks right next to it? Will that damage anything, or at the very least tear a hole in space and time?

YES. Totally fine. Just engage the "seperate" button and you are good to go. If no hum, you know 100% immediately nothing wrong with the 509 and that the problem lies with the interaction of mixed grounds with the home theater gear; This kind of stuff is a large reason why I have separated the home theater from dedicated 2 channel playback. It has been my experience over the years that you only get sub optimal sound on both fronts; YMMV!