Hum when using analog 1/HT bypass with Uniti 2

Have you tried the signal ground switch? Floating vs chassis?

I presume you are hooking up an AV receiver to it?

What you seem to be experiencing is a ground loop hum. It's quite common in complex setups, when grounds are connected at various points. 

If that's the problem, the most effective way to cure is to get an 'isolating transformer' like this. I use two of them in my H/T setup - one for a connection to my pre-amp and the other one for the subwoofer.

joerand posted:

Have you tried the signal ground switch? Floating vs chassis?

I did change from one to the other, left to right, not sure which is which. It reduced the volume of the hum but did not eliminate it. 

Adam Zielinski posted:

I presume you are hooking up an AV receiver to it?

What you seem to be experiencing is a ground loop hum. It's quite common in complex setups, when grounds are connected at various points. 

If that's the problem, the most effective way to cure is to get an 'isolating transformer' like this. I use two of them in my H/T setup - one for a connection to my pre-amp and the other one for the subwoofer.

Correct. 

Looks like this this is next up. Fingers crossed. 

Thanks for the help fellas. Hopefully I can get this worked out. 

The transformer costs around Eur 10. 

Is it possible a failing power supply could be cause of the hum?

Not really - otheriwse you would hear the hum on all inputs.

As Adam suggested ground (earth) loop sounds most likely - is anything different with earthing  compared to how you had set up before moving? Bsaically this most commonly arises if receiver and amp are both earthed and the interconnect ground is connected at both ends. The simple solution is usually breaking that loop, which the signal ground switch that Naim preamps have is designed to do. However if that fails then the isolating transformer should domthe trick.

The other possibility given that things have been relocated is something now close to the receiver that is inducing hum. To check for that try moving it - just lift it and move a foot or two from present position while connected and seleced, and see if any change.

Adam is right.  I use a similar isolator.  Solves it.  Disconnecting CATV cable where it enters the house also solves it, but no CATV is not a practical solution, is it?

Nick