Audible High Pitched Hum... Advice Needed

I have an odd issue that I can’t quite wrap my head around. As the title suggests, I’ve been fighting a high pitched hum in my system and I believe that I’ve found the source but I’m looking for some solutions. I have a complicated system so let me start with a description.

I have a combined 2 channel and home theater setup. Starting with the two channel sources, I have a Mofi ultradeck turntable feeding a Parasound Jc3 jr phono pre and I have a Lumin T2 streamer/dac all feeding a Simaudio I-5 integrated amp and a pair of Kef LS50s. This amp also has a HTB input that I feed from an Emotiva XMC-1 to power my speakers for home theater. I have my TV which is a LG C3 connected to my XMC-1 via HDMI ARC for home theater. Everything is connected to a Furman Elite 15pfi power conditioner on a single duplex. I have the turntable, phono pre, and the streamer grounded together via their respective grounding posts. I have no options to ground the I-5 or the XMC-1. I’ve got things connected single-ended at this point but I have tried balanced out from each the phonopre and the streamer to a TVC passive volume control that I have to convert the signal and I still have the same hum behavior described below.

Okay now thats out of the way, this hum is constant no-matter the volume and is only present when the TV, Emotiva, and I-5 are powered on in my home theater setup with the I-5 input set to HTB. I’ve isolated the hum to the input from both my phono pre and my streamer. If either of those two pieces of equipment are plugged into power and the I-5, I get the hum. It doesn’t matter if those units are powered on or not, the hum is still present. However if I leave everything plugged in and I disconnect the power cords for the phono pre and the streamer - hum disappears. Or - if I change the I-5 input from the HTB to any other input - hum disappears. The hum also travels through both channels even if only a single RCA cable is plugged in. This leads me to think that I’ve got some type of ground issue through the XMC-1 that is exciting something in the unit. The hum doesn’t sound like a ground loop to my ears although I’ve only listened to one online.

Another piece of evidence that leads me to think its ground related is I have my PC plugged into the TV directly for gaming. I get really horrible coil whine from my graphics card leaking through the system but only with the phono pre and streamer connected. If I disconnect those - you guessed it - hum gone. I hear some really strange sounds when I simply touch the HDMI cable from the PC to the contacts in the TV that pass through the system even without the cable being completely plugged in. I was thinking that maybe some DC from the computer power supply could be the culprit.

All that being said - my cabling is pretty tight behind everything but I’ve done my best to move signal cables away from power cables. The hum does not change if I shift my signal cables around. All of my interconnects are high quality from DH labs or Bluejeans. I’ve done some research into DC offset but I don’t think I have that issue as the sound is 100% coming from my speakers.

Any thoughts would be greatly appreciated! I’ve done my best to describe everything I can think of but I’m happy to share any additional details. I can live with unplugging things to eliminate the hum when I’m watching TV or a movie but it really defeats the purpose of having a combined system.


@ajnackman Why do you have the streamer grounded to the same place as the phono? That's a recipe for a ground loop. Won't the streamer work without grounding it?

I've tried it both using a common ground location and keeping the streamer ungrounded without any audible difference or behavior to the hum. The turntable a phonopre require grounding together or I get noise issues.

So I purchased an ART DTI dual transformer isolator to try out and installed it between my AVR and my integrated amp - the reduction in the hum is impressive. If you stand right next to the speakers you can still hear it - and I can hear some of my other input leaking through at very low volume if I have my Dac playing. Overall very impressed for 80 bucks. 

ajnackman OP  Good to hear that it worked.  The one I recommended probably would have done the same thing with no noticeable audio degradation for $8.90 each. You could have gotten 8 or 9 for the same price as the ART DTI.  One for every input!

Did you check everything concerning your cable box? Have the cable company check it making sure it is grounded correctly.