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
Ajlimke --

Given you are encountering the hum in both cases; have you experimented with the physical placement of the phono stages (relative to any other equipment, the interconnects & any power cables that you are using).

Cheers -- Bish
Adding to Bish's comment, I tried using a small high intensity desk lamp beside my table, and the transformer produced a crazy hum in my phono pre. I have an lehmann se currently not in use and it's dead quiet. I have read previously also that Grado's pick up motor hum from rega tables. I would do some moving around of pieces to see if your phono is picking up interference from another component (or lamp) for sure
Check your cartridge clips if they're connected properly.
Any clip weak or loose?
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.
The Lehmann uses a toroidal transformer in its power supply, and toroidal transformers don't react well to dc offsets that may be present on their ac input. A common symptom is mechanical buzzing that is emitted directly from the transformer, but I believe electrical noise can also be introduced into the power supply circuits as a result.

I would suggest placing your ear near the power supply and listening, with the room otherwise quiet. If you hear mechanical hum being emitted, I think it would help to confirm that theory. In which case, search prior threads here under "dc offset" + "toroidal" for suggestions on how to deal with it.

Also, if there are any dimmer switches in the house, turn them off. They can introduce dc offset, noise, and other anomalies into the power lines, as well as radiating emi/rfi through the air.

-- Al