Hum with non-Naim source

I know this is an age old problem but once again…

My system : 252/300, dCS bartok/clock, harbeth shl5. Interconnects mostly witchhat morgana.

Bartok is plugged into 252 CD input with morgana RCA-DIN interconnect

When volume turned up to 12 o’clock. An audible hum from the bass driver … but just normal hiss through tweeters.

So I think there’s an earth loop. Since this is a non Naim source…

Connecting the raw earth with 252 made the hum even worse thru speakers (I.e earth wired into a UK plug and connected to 252 signal ground)

So what’s the solution be? Connect the chassis ground on bartok to 252? Any suggestions welcome. Reading thru other posts left me a bit more baffled so…

Your 252 will be expecting a ground connection via the source. On an all Naim system that would be a CD player or streamer. If your Bartok can’t provide that, it may cause a problem. Also, if you have two or more grounded sources connected, it could create a ground loop.
Having said that, 12.00 is pretty loud for a Naim preamp, so perhaps a bit of noise is to be expected.

Yeah I know it’s pretty loud at 12 o’clock that’s hardly what one would describe as ‘normal’ volume range

Though the hum is quite distinct. So wish to find a way to reduce it.

I used to have a CDX2 years back then. When the SN1 turned to 12 o’clock there would be some background hiss but no hum. So that’s what I am after …

From your description it sounds more like a small amount of residual hum that you can only hear at high volumes rather than hum caused by a ground loop. A quick look at your system in the system pictures thread shows a pretty stacked set of racks with more sources than just the DCS. It also looks like you have some Entreq kit and what looks like a mains regenerator ?
I would take a look at your rack wiring, making sure that mains and signal cables are well separated. How is the Entreq connected ?

I have removed the Entreq from the system.

Cable dressing wise generally tidy but will look into that Thks for reminding that. Can be this

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