How far is your SUT from your Phono Pre/Preamp?

You don’t happen to have the SUT plugged into a different electrical outlet? 

I've spent the morning doing a bunch of things, reorienting, finding weird angles, and changing cables to shielded cables. Cables make no difference at all. There's definitely one spot that I found to place the SUT that is the quietest and it's about 14 inches away which is good... but there's still a noticeable hum, although only within 3 feet of the speakers, not in the listening position.

My question now is whether the hum is the fault of the SUT or the phono preamp? Will any SUT that gets near my phono preamp cause a problem? Probably need another SUT to figure that out.

Is the SUT or the phono stage in close proximity to your amplifier? Could the power transformer in the amp be the cause? Just thinking out loud....

@atmasphere  : this comes from my post: " ( an even of the SUT it self. You can rotate it for example.  ).

R.

@dhcod  : Why do you need an external SUT with your Lamm PS De Luxe? 58db plus the line preamplifier gain is enough for your 103R.

Now, in the other side : Have you in the past that kind of hum problem using your Lamm with out external SUT or made any analog rig change when you got the external SUT?

If you made any analog rig change the 103 is an easy to be contaminated and develops some kind of noise as " hum " if those cartridge/tonearm connectors are not tigth secured.

R.