You might also want to check the RCA's on your interconnects to make sure the pin is firmly engaged by gently putting pressure on them in a circular motion. If the hum disappears either completely or intermittently during this procedure, you probably found the source. Standard design female RCA's are notorious for this. A very worthwhile upgrade for any component in my opinion is to replace them with WBT's which have a two-piece spring-loaded receiver that clamps down on the pin.
buzz from one phono preamp more than another?
My Lehmann black cube se makes way more buzz, enough to be annoying, than my Grado ph-1. The Grado buzzez as well , but just barely. I've been back and forth w/ three prong adaptors, different circuits of my house etc. and have run out of ideas. Except a power conditioner. Would that help? I hate spending a lot of $ on something for no results. I'd just swap them out, but the Lehmann sounds better on my stereo. No hating, I even have a brand new Grado Reference Sonata 1 cartridge($5-600 new) that sounds absolutely killer. Except for the hum on the Lehmann. Any ideas would be much appreciated