Problem with a new Emotiva XPS-1 TT pre-amp: THUMP, THUMP, THUMP...

Hi, I just added an Emotiva XPS-1 phono pre to bring my old/only TT (Kenwood KD-38R) into my new Raven Audio Blackhawk amplifier. (Please, no hurtful jokes...)

Anyway, sometimes when I lift the needle, I hear (*loud*) 60Hz popping, actually a continuous THUMP, THUMP, THUMP. It occurs whether the platter is still spinning/needle lifted or platter/stopped. The pop stops when I drop the needle,  however, and starts again when I lift the needle.

I didn't have this problem with TT connected to built-in pre on Denon AVR3802. Is it the Emotiva? Is this a "burn-in" issue? (BTW, any suggestions on burning-in this unit that is supposed to be left on all the time?) I'm not panicked - should i be? 

• Note 1: everything (Amp, Pre, TT) is plugged into a common 3-wire power strip. Ground wire connected from TT to Pre. Both XPS-1 and TT are 2-terminal power cable though.
• When I unplug/replug Emotiva XPS-1 back in, the popping stops  until I lift the needle again.
• I tried plugging into different outlets...
• TT is grounded to Emotiva XPS-1

That said, the sound experience appears to be improving with each LP (but Day 1).  Any ideas what's going on with this preamp?  Thanks for reading!

(FWIW, here are the first LP's I played to christen my system: Rush/Permanent Waves; Michael Hedges/Aerial Boundaries; Freda Payne/Golden Archive Series; the dB's/The Sound of Music; and Yes/Big Generator.)