Do ground loop isolators coax degrade sound?

Here's another in the endless series of ground loop questions. Ive had a nasty ground loop after switching over to my new D-sonic amp in my Ht system. As typical in these situations, the culprit was the cable tv box. I tried out an inexpensive ground loop isolater from TII technologies which solved the problem elegantly. However, my ears tell me that the volume is reduced slightly and dialog is a bit harder to hear. I dont see why as I use the HDMI out form the cable box to my processor. So folks is this an illusion? Would I be better served by a more expensive model like the oft recommended Jensen?

http://www.jensen-transformers.com/product/vrd-1ff/Thank you in advance for any thoughts or comments and recommendations.[/size]

Maybe the low cost T2 solution is too aggressive on flitering? Here is the T2 product info : http://www.amazon.com/TII-220-Ground...=A1SRR0B7QVPEN. Or here : http://www.tiitech.com/repository/da...DS039-0710.pdf