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

I believe I have heard something similar to this before - twice - but both were some time ago - the first time it was definitely a router. Turned off the router, problem went away. Someone near you may have a powerful router. That would explain why you do not hear it when you take the preamp elsewhere. Try putting the EAR next to your own router and see if the sound gets worse.

The second time, if I recall correctly, I believe it was a combination of my iPhone 6 and a Grado Sonata 1 cartridge (an unshielded cart) going into a Croft Micro 25 (12AX7's) - but it was intermittent. I was trying to record and occasionally a similar noise would cut in intermittently. I put my phone in airplane mode and the problem went away. It may not manifest in another location with because your cell may be working on a different cell frequency elsewhere or your phones's GPS was turned off, or your bluetooth was not connected to anything..etc..; I do not seem to have the problem any longer with my latest iPhone.

- I'm not using any switching power supply anymore with the dac nor with the streamer. 

- The problem with the phono preamp was there since I bought it, about three months ago. I have tried unplugging everything, even a freezer.

- Plugging in the DAC didn't do anything which basically means if I use a different turntable, it's won't solve the issue. 

- Ferrite cores are on the list, I'll definitely try the 100K grid stopper.

- Yes, I'm using a streamer but it was unplugged of course. Both the DAC and the streamer are powered from Allo Shanti linear PS. 

- Switching the phones off didn't help.

One more important thing to mention is the interference can be also received by the line stage - ARC LS16. I noticed it when I was switching tubes. It only happened when I opened the top mesh though. I'll try again now before I move the preamps to the opposite side of the room. That would confirm the signal is being caught from the air, right? 

- I have tried to bring the phono preamp closer to the wifi router, It doesn't seem to have any effect. I'll try again and share the changes. 

The strength of the signal depends on the height level of the the preamp. The higher I hold it, the stronger it is. I doesn't change above 1,5m/5ft but it changes with every inch closer to the floor below 3ft. 

I think it's the input of the preamp that is sensitive. It's even more sensitive with RCA cables plugged in. It's interesting that even with the input exposed the signal changes when I squeeze the output cables together, still, it never goes off completely. That's basically all I'm sure of right now. 

Thanks for the help, I really appreciate it. 

Agree, that the DAC plugged into the Phono would appear to be like a TT at first glance, however, completely different grounding protocol, and completely different sensitivity to the outside world and interference. 
 

Which EAR-834P model is it?

have you tried eliminating the ground, period.

MP 200 is poly alloy cartridge and in theory is like a moving iron cartridge. I had a similar issue and eliminated the ground and the pulsations and noise went away. This was with a tube phono section from Audio Hungary. Went SS now with SPL.

If it is louder near the floor, could it be the source of interference is in your downstairs neighbor’s apartment? How many floors in your building? 

Another thought, it might be worth investing or borrowing test gear that would allow you to positively identify what type of interference it is. For instance, if @theaudioamp is correct about it being a demodulation, perhaps an oscilloscope trace could prove that. just a thought.