Phono Stage Hum


I have been experiencing hum on the input from my phono preamp. In the past, any problem like this has typically resulted from a ground issue, but the ground seems to be well grounded. The hum/noise starts somewhere around the 25% mark on the volume.

The system:

KAB modded Technics 1200 w/ Audio Technica 150 MLX Cart.
Zu Xaus cable
Jolida JD 9A phono stage (high output line out)
(I have it set to no gain, but to the impedance to match the cart.)
Zu Gede
Jolida JD 102B Integrated

I have a second system that I can run my turntable through to trouble shoot. I don't get any noise over the line from my DAC (fed by my cdp and my digital library).

Any thoughts as I start the troubleshooting process?
tjnindc
I think it might be something external. I have slowly dismantled and reassembled my system. I also reset the impedance on the phono preamp. I have reduced the noise/hum significantly but just discovered that at very high volume levels (with nothing playing) that it is picking up radio signals!?!?! It does not happen when I run my turntable directly into my Creek. It does happen over either amp when I introduce the Jolida phono preamp.

Right now, I have the gain set to the factory recommend and I'm running out on the "low" line out. The sound is great, and I never really get to the 50% point on that amp with the Druids, but it seems like there *should* be someway to clean up that noise.

I did recently read a review on 6moons of a device that is supposed to clean up external fields (if I remember correctly).

Tim
The Zu Xaus is shielded. I think that I need to:

1: Play around with the cable from the phono pre to the integrated.

2: I've heard that using a three to two prong adapter on the phono pre power cord at the power conditioner can help.

The problem is volume sensitive. That leads most to think that this is not a ground issue. I don't always get the radio broadcasts which is strange but also seems to support the idea that it may be driven by external interference. I guess the challenge is figuring when it is introduced.

I've swapped the cartridge to confirm that makes no difference--it did not.

Any other thoughts? Anybody know the acoustic revive equipment?

Tim