B135 REC Output HUM

[Raystar]

Hi,
I am trying to determine the source of a loud buzz or hum that occurs when the REC Out connections are used on my B135. I normally have an SC-1 SugarCube connected to the REC OUT RCA jacks for removal of clicks and pops from the phono input but any source I connect (ie. Tuner, CD etc.) by RCA interconnects only ( no AC) has the same buzzing. With REC Out connections removed each source is dead quiet. I have physically moved the B135 to another circuit in the house and tried each source connected separately with either the Sugarcube or a tape deck or even an isolation transformer in the loop but the result is always a loud buzzing. Any thoughts would be appreciated.

Thanks