Couple more thoughts and experiments:
* I did a brief read on Shunyata and their power distributors. I might have missed it, but they did not call out specifically how their internal distributors actually work and corresponding components. It might be worth doing a YouTube search to see if someone has opened up a T6000 to actually see what components Shunyata is using in your distributor. The website refers to toroids, transformers and capacitors, but it is really unclear what actual parts are used in this device. If no one has opened up their T6000...be the first to do it and see if they have transformers, caps, toroids or if this is merely a "power strip"
* Cheap and easy....borrow an AC line conditioner, regenerator, etc. from a friend to see if it makes a difference, for your preamp. As usual, scientific method (plug this borrowed line conditioner into same outlet that your preamp is currently using and only plug the preamp into this device. If no difference, then one by one add more of your stereo components. You are trying to see if another device (close proximity) is creating the noise.
* Remember....as I found, multiple number of man made /house appliance and device RF noise sources could exist and no silver bullet. As audio2designs reminded me, even devices such as dimmer switches can be a source of noise transmission that is picked up and amplified by your preamp.
* The torroid I specifically used (and was recommended), mix 31, is designed to trap man made noise low frequency such as transformers, walwarts, etc. If you do a quick google search to see what other people have done and their results, you will see pretty good results. Not a 100%, but again like insurance, you have to have layers of filtering for pesky noise inducing situations. That is why I could easily hear reduction in noise in my music room. Will I have to explore other possible capacitors, transformers, toroid mixes? Yes. Will only one component solve all MY issues....nope. Hence, keep an open mind to the different possible noise trap solutions and the different sources of noises...which leads me to....
* A cheap and easy way to "hunt" for man made / house noise is using an old battery operated pocket AM radio. Go outside away from your home and away from household noise inducing devices. Set the AM radio to the top of the band, 1600 (1600 kilohertz), or something close to that range that does not have a broadcast signal. Listen and learn for the speaker noise and pitch on that non broadcast signal. Now go back into your stereo room and put the radio near each transformer, device, light switch, light, computer, etc.. Your going to use this device as a noise transmission detector.
Slowly turn the radio 90 degrees relative to the device and within 6 inches from each household device, switch, power strip, walwart, etc. If you hear a change in pitch/noise.....your on to something. If it is a light dimmer, for example, maybe it is an old dimmer that needs to be replaced. If it is a new device, then you will need to get creative on how to eliminate the noise transmission from that device. In my garage I have a battery tender for my car. The battery tender is relatively new but it is located near my ham gear. I A/B tested (before toroid / after toroid) with the toroid and noticed a small but perceivable reduction in noise. Again, you may have several different devices that contribute to the noise so you have to prepared to hunt for different noise sources and use different techniques to suppress / kill noise.
Happy hunting, Mr. Wick.