The first thing to check is that the Cogeco RG6 cable is properly grounded where it enters the house. If the ground loop is caused by the incoming cable (the most likely cause in this case) it may fix the problem. That is accomplished by running a minimum #10 wire from a grounding block on the cable to the household common ground used by the house panel (not the panel itself.) That is Cogeco's responsibility. Failure to do so is against the Canadian Electrical Code and could cause injury and property damage.
Beyond that, it is your responsibility to track down ground loops inside the house. The best way to remedy is with equipment isolation. That may be done by inserting a 75 ohm isolating transformer on the incoming cable, after the grounding block. That may affect the cable signal if it is not a good quality device. Cogeco may be able to supply one.
The loud hum is caused by the 60Hz ground loop signal entering cables or equipment. Poor quality analog audio cables are easily replaced with heavy gauge cables but better quality equipment can be expensive. One remedy is to use fibre optical cables where possible. That can be done with many audio devices. Unfortunately, the common use of HDMI for video and audio does not allow that with other devices. Bonding equipment to a common ground is another solution. That can be done by using a common power bar or common panel circuit for all devices. Another way is by using a heavy gauge cable or connecting a grounding conductor between the problematic devices. In some cases, ground loops can be caused by faulty household wiring. That should be tracked down and corrected by a qualified person.