Many thanks to Bob_bundus.
I researched the Forum and found a solution which works for me. I grounded the incoming CATV line to an isolated ground near the house ground. It was poorly grounded to the outside electrical box cover, which introduced paint into the ground path, and and this connection was further degraded because the ground path now includes the mounting screws of the box, more paint. I then floated all the system AC grounds to allow the interconnects to carry the ground... no ground loops, no hum, no 'hardness' in the sound and picture. (Grounding the amp in this configuration causes a definite hum). Using the MAGIC, I lost some of the baseband and premium channels. Note, there is a very small resistance between the house ground and the isolated ground, and this this is simply the soil resistance between the 2 grounds... verified by poking the voltmeter probes into the soil near the 2 grounds. However, there is no voltage difference. The code says to ground the CATV to the house ground at the point of entry, and if I could get direct access to the house grounding rod, I would prefer to use it instead.
I researched the Forum and found a solution which works for me. I grounded the incoming CATV line to an isolated ground near the house ground. It was poorly grounded to the outside electrical box cover, which introduced paint into the ground path, and and this connection was further degraded because the ground path now includes the mounting screws of the box, more paint. I then floated all the system AC grounds to allow the interconnects to carry the ground... no ground loops, no hum, no 'hardness' in the sound and picture. (Grounding the amp in this configuration causes a definite hum). Using the MAGIC, I lost some of the baseband and premium channels. Note, there is a very small resistance between the house ground and the isolated ground, and this this is simply the soil resistance between the 2 grounds... verified by poking the voltmeter probes into the soil near the 2 grounds. However, there is no voltage difference. The code says to ground the CATV to the house ground at the point of entry, and if I could get direct access to the house grounding rod, I would prefer to use it instead.