I have a weird buzz issue; can you help me solve the problem?

Hi - my integrated amp has a 25db persistent buzzing noise; I need help figuring out how to solve this problem.

Here’s my system:
CODA CSiB integrated amp - custom tuned to produce 25w Class A power before switching to Class B
Lumin T2 streamer/DAC
Dynaudio Focus 380 speakers
Audience AR2-T2 power conditioner w/Audience power cable
Audience AU24 speaker cable
Cardas Clear M power cable
Purist Venustas Luminist Revision RCA interconnect
Synergistic Research TeslaPlex SE outlet
Shunyata Venom Defender

Some background:
I’ve had the CODA integrated for about 5 years. The remainder of my system has come on-line subsequently (I had different speakers initially). Within a few months of purchase, I noticed a buzzing noise coming from the speakers whenever the amp was powered on (bias “on”), but no noise in standby mode (bias off). I took it back to the manufacturer, who plugged the amp into their dedicated circuit and it was dead quiet. I had the same experience taking it to a local audio shop. Thinking that it might be a noisy circuit, the local shop loaned me a lesser priced solid-state amp (I forget which brand) to bring home. I hooked up the shop’s integrated to my system and.....it was dead quiet. Now I was confused. 

A dealer loaned me a completely different system with a tubed integrated, different speakers and cables. There was even a worse buzz coming from this system than from mine. I went back to living with my system and forgetting about the buzz.

Fast forward 4+ years. I have moved to a new house in a new state. Unfortunately, the buzz remains :-( I even tried plugging the system into what the electrician was sure was one dedicated line in the house (it was in the kitchen, so I had to run an extension cord to where my audio system lived). Still, the buzz remains.

I really love the sound of my system, but this persistent buzz is a (ahem) buzz kill (sorry for the predictable and bad pun). 

I would love to get some thoughts on what I can do to get rid of this damn noise. Please help!

To cakyol: I tried your suggestion of plugging the amp and streamer directly into the wall (no power conditioner). It made no difference, the buzz was still there. I also tried just the amp alone into a regular outlet (no streamer); the buzz remained. I vaguely remember that I purchased the power conditioner in the hopes that it would eliminate the buzz, and even though it didn’t, it had a positive effect on the sonic quality of my system.

So where, in your opinion, does this leave me?
To oldhvymec: my speakers only have one pair of binding posts, not two, thus I could not try your suggestion. 

I have multiple built in appliances in my house and thus could not unplug everything as you suggest. A previous suggestion was to turn off all the breakers except for the one to the stereo. Will this work as well as what you suggested?
It sounds like a ground problem.   Integrated amp, plugged with a cheater ( no ground ) directly to the plug, no inputs, nothing else, and you get a low level buzz that is leaking into the amp circuits.

Perhaps the outlet is wired backwards, it happens.   So, the "neutral" is on the wrong side.   That can wreck havoc depending how the power supply is designed.

Have you tried other outlets in the house?   I think you said you ran one to the kitchen...  You can't always trust the electricians.

Get an AC outlet checker at a hardware store.  Check to see if the outlet is wired backwards.  It's cheap and easy to use.  It is possible that your old house was also wired off.   
I have multiple built in appliances in my house and thus could not unplug everything as you suggest. A previous suggestion was to turn off all the breakers except for the one to the stereo. Will this work as well as what you suggested?

Yes, but in the event it does go away, you'll be doing what I said to isolate the offender, anyway.. Either way.. will work for the test though.

Built in, I'm not worried about, too much. WHY. because you brought your noise with you, you've moved.. Not saying a common appliance isn't a problem.. chances are slim, though.. just saying..

I suggest an extension cord, only to get away from whatever is in the room. Turn all the breakers off including the room the stereo is in.
The room you choose turn back on and plug into. Make darn sure, nothing is plugged in, in that room, except the extension cord, back to your stereo..

After that only thing is drop the voltage down.. If It was a tube unit, we would have looked at possible noisy valves too.

Your getting there..hang in there. one way or the other...

Oh and BTW I bought a plane ticket to come fix it. My ticket is for Cancun Mexico... Oh you don't live there.... opps.. can you meet me there..LOL

The next step would then be to make sure that all the signal cables you have are shielded like a coax cable. I had a problem like that once and it got fixed when i changed the signal cable. I presume your cables are good but just be sure. 
You can also try moving JUST the amp to another mains plug in another room, put headphones on and WITHOUT anything connected to its inputs see if you also get the buzz. I have a feeling your streamer and amp are having a ground loop issue.