I had the same problem whenever I had my DVR connected to the DAC in my system. It's a hum coming in the cable coax in my case. Was faint at my Westlake, OH location, really five times louder here in Chardon/Munson, OH. This device from amazon solved it, completely, with no sound quality detriment:

https://www.amazon.com/Viewsonics-VSIS-EU-Cable-Ground-Isolator/dp/B0017I3K9M/re...

If you have cable, this may cure your problem.

Try plugging the SE84 directly into a wall socket instead of the Furman.  I read some place on the site that Steve suggests not using a power conditioner.  If you want to protect the SE 84 from line surges Steve suggests using an isolation transformer.

I'm not sure anything including the Furman will protect against a direct lightning strike.  You may want to check with Tripp Lite to see what they say.  Steve's paper on power cords is where he mentions isolation transformers.
https://www.decware.com/paper70.htm

I use a voltage regulator from APC that I directly plug my SE. 84 into.  I also plug a Tripp Lite surg supresser into the APC and then plug all of the SS gear into it.  The APC is plugged into the wall using a good quality commercial reseptical.  I have no hum with this setup.  

We don't get much lighting out here in the Pacific Northwest.

One last thing.  Tripp Lite makes two grades of isolation transformers.  On some  reviews of their standard ( black) transformer people have said that they here a low hum coming from the transformer itself.  Steve suggests using the hospital grade ( white ) one.