I have experienced the same thing with the 'crawl' on the TV screen, and yes, this is definitely ground-loop-borne. Furthermore, if I turn the gain way up on the 990, I can hear the line noise (60, 120, 180 etc Hz) whereas if the cable is disconnected from my Motorola DVR (but all connections left intact from the DVR to the 990) the hum immediately disappears (completely) and the screen crawl stops. After $inking what I have into amps, speakers, pre/pro, HDTV etc, the thought of just 'living with' the hum and crawl just doesn't cut it.

One simple fix that I have used is to take two 300 Ohn to 75 Ohm 'baluns' (Radio Shack or equivalent) and wire them back to back. That is, solder the two pair of 300 Ohm terminls together, resulting in two 75 Ohm screw connectors. This effectively isolates the grounds but lets the signals pass through. With this in place there is neither screen crawl nor hum from my system...and the fix costs all of about $9.00 to implement.

However...what I have noticed is that there is definitely a loss of signal to noise ratio on the 'lower' tier of cable channels (and regrettably, I seem to have made a rather effective notch filter for channel 7 in the process), though those above 100 or so don't seem to be adversely affected one iota. Fortunately for me, I don't watch those channels much (and more importantly, neither does my wife...), so that really doesn't bother me. Another plus here is that the HD channels don't seem to be affected at all either....so I'm willing toi live with the lower S/N on the channels I seldom watch. Compromises...

Cool thread though...I'll have to check out what some of the others have proposed. Maybe I can eliminate the ground loop hum and crawl, and not lose as much signal (on the lower channels) in the process.

One last bit...can anyone here say how good the proposed isolators are in terms of maintaining signal to noise ratios on aALL channels?

Mark