Newbie hook-up question w/ ARC PH-3 SE

I've just purchased a second-hand ARC PH-3 SE. I hooked it up to my LS-2B MkII, and an old swiss-made Lenco turntable that I borrowed from a friend's dad. When I turn the system on (and volume up), all I hear is a loud hum coming out of my speakers. Did I connect the ground incorrectly? When I disconnect the turntable from the pre, the hum disappeared.
I'm not familiar with your gear, however it sounds like a ground loop problem. Does your pre have a ground post for your table? Wish I could be more helpful.
Other people at a different forum have also suggested that it is a ground loop problem. I will check again.
This combination (Lenco + AR PH-3 SE) is analagous to putting a 2-stroke motorcycle engine in a Mercedes. The critical issue is what cartridge is in the Lenco. Then, make sure that the PH-3 is set up appropriately for gain and load.
Try not connecting the ground. I have a PH3 SE and Ref 2. It sounds MUCH better without the ground connected. Also if you bought the PH3 second hand, someone might have loaded it innapropriately for your cartridge.