Tube PHONO preamp interference - RFI, EMI, bad grounding?

It’s possible that we are arguing because our two countries have different codes re grounding. Everything I have written is based on how things are done here in the US. The 3rd prong of the IEC is earth or AC ground. Correct? We see here that there is a 33 ohm resistance between the 3rd prong or earth ground and a screw that we agree is a ground lug. I take it to be the back side of a typical grounding scheme to be found on many phono stages which is to be used to ground the turntable or tonearm. There is no significant current or voltage on the ground wire coming from a turntable chassis or a tonearm, so there is no danger of blowing that 33 ohm resistor and making the chassis dangerously "hot". This is why EAR could get away with what appears to be a 1/4 Watt resistor or 1/2 Watt at most. By my way of thinking, that 33 ohm resistor is to float the AUDIO ground with respect to earth ground. We also see that the screw is directly connected to the PCB, and I assume it is soldered to the ground plane. This is not dangerous and is a ploy to reduce noise. For me to be correct, I would need to know that (1) the screw we see is NOT touching the chassis, and conversely (2) the 3rd prong on the IEC connector is directly connected to the chassis. (That would mitigate your legitimate fear that the chassis is floated.) So, the lug and the audio circuit are both floated by 33 ohms over the AC or earth ground and the chassis. That is OK in the US, where the AC receptacle is connected to a solid earth ground in every home that is up to code, by the 3rd wire.

I am not an EE, so I would welcome correction if I am off base. I don’t want to be giving advice that may lead to a dangerous situation.

By my way of thinking, that actually makes the most sense if you are going to float the audio grounds; you want the upstream gear to be grounded at the same potential as that of the on board audio circuit. It seems that you want the ground lug to be at AC or earth ground, which is certainly not "wrong" either.

@lewm You want the ground post at chassis potential, not the audio ground. The grounding system is supposed to be ignored by the audio.

So the ground post is simply bolted to the chassis, along with the center pin of the IEC connector. The 33 Ohm resistor is then placed from the audio circuit ground to the chassis.

This sounds like an easy fix! It may not fix the RFi, but it won't hurt and it will make the unit safe and in compliance with EU directives.

So that 33 ohm resistor we see in the photo, which is in series between the threaded screw and the 3rd pin of the IEC, according to the OP, is either doing nothing or the chassis is floated by the 33 ohm resistor which I certainly agree is not the best idea. The OP has dropped out so we may never know. I am going to get my meter to see what’s up with the ground lug on my Steelhead. It looks to be isolated from the chassis.

@lewm 

So that 33 ohm resistor we see in the photo, which is in series between the threaded screw and the 3rd pin of the IEC, according to the OP, is either doing nothing or the chassis is floated by the 33 ohm resistor which I certainly agree is not the best idea. The OP has dropped out so we may never know. 

We knew this days ago when the OP confirmed the chassis is 33ohms above ground. He measured it. 

@atmasphere and I have been trying over the past few days to guide him in the right direction - ground the chassis and ground lug to 0 and leave the circuit ( board ) floating at 33 ohms.

Ok. My idea that floating the ground lug above ground along with the audio circuit is unconventional at best, based on what Atma wrote and my own measurements of two phono stages at my house. So I expect the ground lug on the EAR is in contact with the chassis. The ground lug is at chassis potential. Therefore I assume the IEC ground must not be directly connected to the chassis. (If it is, the 33 ohm resistor does nothing.) So, the 33 ohm resistor floats the whole device, chassis included, with respect to the IEC. That IS strange.