Have you tried a cheater plug? It eliminates the ground loop hum. Most likely your problem. It's a 79cent fix.
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Hi I would try the cheater plug which you can get from a Dollar Store 2 for $1. If that does not work I would tighten down the transformers on the chassis and place some
neat dampening blocks under it. Check your polarity to make sure it's correct. Some people will reverse the wall plug and get great results. Some people have problems with Line Conditioners too. Take it out of the loop. Sometimes your tubes may be weak and need replacing or rebiasing. Just some thoughts! Also check the tubes in the preamp. With the cover off and the volume cracked open
tap the tubes with a pencil eraser. If you hear noise coming through your speakers turn off everything and unplug the gear and clean the tube pens with an exacto knife then isopropyl alcohol and treat it with some Pro Gold, etc. If one those don't help hmmmmmm!!!!
Please see the following excellent reference:
As you'll see, interconnect cables are usually key factors in how hum/buzz is introduced into a system. They should be kept as short as possible, and should be chosen to provide low shield resistance (although unfortunately that is often not specified, and trial and error among different cables may be the only way to tell).
My Pioneer 51FD Blu-Ray player makes a "whooshing" noise when I play DTS HD-Master music disks (Dolby True-HD, DVD and Blu-ray are very quiet).
My Toshiba A35 HD player is just plain NOISEY! (cheap casework)
I've purchased a four-bay equipment rack with a plexiglass "front door" to try and block the noise.
I'm putting the whole thing together tomorrow and will see if it works out.
The ground loop theory is your best lead to follow. All of your components should ground at one location in the wall, and only one component with a ground plug, float everything else with a cheater plug. Be sure your AC receptacle has good spring tension. Many times the tension is so bad that the plug nearly falls off the wall....now that is a fire hazard. Get a Hubbell or hosp. grade AC outlet and this is contact. Jallen
Is the hum coming out of the speakers while the system is turned on or is it coming form the amp when it is turned on? The cj mf series does have a slight transformer hum when turned on. I owned one and it was never bothersome..........couldn't hear it from my listening chair. If the hum is coming from your speakers while the system is powered up then try lifting the ground with a cheater plug as suggested above.