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New Hum from phono section (Project Phono Box MKII)

I have developed a new hum from what I assume is the Project Phono Box MKII. I have only been back in vinyl for about a year and it has sure changed since the 70's. When I first hooked my turntable and phono into my system it had a hum. Not unexpected, but cured by connecting a ground from the turntable to the phono and on to the pre. Nothing has changed electrical in my house for ages. I do not have grounded plugs (joy of living in an old not updated house!) and have only once had a ground loop from the Vandersteen's and that was in a downstairs theater.Cured it by running a dedicated ground to an outside ground post.
Symptoms:
1. New problem that just happened, everything has been fine.
2. Noise increases as volume is increased.
3. Sounds like a loud ground loop hum

Tried So Far (none worked):
1. Isolating turntable from phono both from interconnects and AC do not cancel noise.
2. Unplugging one interconnect from phono to pre decreases noise but does not cancel.
3. Plugging system into a different wall socket on another floor of the house.
4. Trying different interconnects.
5. Ran a isolated ground to exterior ground post and connected grounds.
6. Unplugged the subs from the system.
7. Switched grounds from phono, turntable, and pre
8. Disconnected all grounds.
9. Isolated Phono Box power supply from the system.
10. This is my dedicated music system and is not connected to any other A/V equipment.

Any ideas? I think it is the Project Phono Box or it's power supply. I appreciate any help as I am a serial lurker and rarely post. My many thanks in advance.
Doug


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Topic - New Hum from phono section (Project Phono Box MKII) - bewareofdoug 16:08:09 11/07/15 (11)

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