Help!

This is my setup:

rega p3-24
ortofon quintet black mc
ortofon st-7 SUT
audioquest big sur cables
rogue audio rp-5 with 40db gain, 47kOhm input impedence phono input
cardas cables
NAD C275BEE amp
KEF LS-50

in a previous setup, I had the rega plugged directly into the rogue with the gain set to 60db and 30ohm load and it was dead silent when the needle hadn't dropped.

my motivation is to use a separate phono preamp than the one built into the rp-5, so I've added a SUT--eventually, I will bypass the internal phono preamp and use a regular line-in on the rp-5.

I've checked continuity on all the RCA outer sheath conductors to ground and there seems to be less than .5 ohm resistance. I checked that all my ground are connected--I have a grounding bar that connects all grounds together, with each ground connected to the bus bar with it's own wire.

but with the addition of the sut, which is also connected to the same ground, there is a hum, even at low volumes (gets worse at higher volumes). when I touch the tonearm, the tone of the hum gets deeper but the amplitude goes up (gets louder).

additionally, with the SUT added and the hum, I can hear the volume knob clicks as I turn up the volume!

Any suggestions?

Thanks!


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