Speakers hum and buzz when rr and dbx installed??

Hi guys and gals, this is my first post here but I have been
an avid reader here for quite some time and have learned alot. Thanks! I have a question concerning my stereo system.
I have a new Jolida JD-801 powering a wonderful old pair of
JBL L300s but when I decided to move my reel to reel tape deck and dbx noise reduction unit into this system from my
ht receiver, I am getting an unexceptable amount of hum and
buzz coming out of the speakers. I have the system plugged into a cheap surge protector (soon to be replaced)and the amp is plugged into the wall outlet thru a gfci. The recepticle is a dedicated ps audio power port on a 20amp breaker. If I unplug the dbx from the tape output on the amp, the noise goes away. I know my system needs attention in the area of power conditioning and I am trying to learn all I can to make an educated purchase in this area. I feel I may have a ground loop going on here but I don't know for sure. Any ideas on this subject and/or recommendations would be greatly appreciated! Thanks!