To use a line conditioner/surge protector or not??

Hi. I recently added a Panamax 1000 surge protector/line conditioner to my audio room. My system includes a Threshold Forte Model 3 SS amp, a Parasound P/LD preamp, Arcam and Cambridge Audio CD players, and Meadowlark Shearwater "Hot Rod" loudspeakers. I also sometimes run an RBH passive sub. I was receiving some low level radio signal through the wall socket (I don't have a tuner!!!), which was audible even when source material was playing. This problem was more noticeable when I used an AudioControl graphic equalizer in-line (I have since taken it out of the system). After running all my gear through the Panamax, the extraneous "reception" is now gone, but I seem to discern an audible drop in my upper-frequency response. I read one thread on another site that suggested one should not use line conditioners and surge protectors in high-end units. Any advice on the subject? Thanks.