Help needed to eliminate unwanted noise from tweeter

The only other things I can think of is to try to connect the noisy components to the input of the E280 and CDP-997 where you know there’s no noise. Also, if there’s enough slack on your cables and wires try holding the noisy component in your hands and moving it around in the air. Maybe it’s too close to a transformer of another component. Maybe the component itself is the culprit? Try distancing/ separating power cables and audio cables (don’t bunch them together. Has this noise always been there? Did you change something recently? Is the noise less at night than during the day? Have you tried a different outlet? If the problem comes from your house wiring you might need an AC voltage regenerator, but they can get very expensive (thousands). This is the only sure way to get rid of any AC noise. A surge protector or filter WILL NOT eliminate noise from your house wiring.

Removing/swapping components, one at a time, you should be able to narrow it down to one faulty component. 

However, the hardest problems are when 2 unrelated factors combine to cause the issue so it could be harder to figure that out.

Removing/swapping is the path forward.

Jerry

No, the tweeter is not the issue. You said it starts when you add in the DAC. It is a problem with the DAC and more than likely it is defective. Try a different DAC if you can. Try the DAC in a different system if you can. Take it to a store and see if they will plug it in for you. 

@ellajeanelle Thanks for your insights on swapping the noisy components to no-noise outlets, that's brilliant idea to trouble shoot.  You gave me "light bulb" that the Novaris PP10 surge protector/noise filter come with 8-outlet, the "noisy" one are first row... I may look into detail if the ground/earth terminals and other (live/neutral) terminals are secured/tightened.

About the noise I described... it's like hissing sound, as I read from google, some said they are pretty normal as my amplifier has a higher amplifier gain of 28dB, my speaker sensitivity is 85dB/m... only when i step closer to tweeter, I could hear the hiss sound.

@carlsbad2 Thanks for your tips, yes, I have done that, I will do few more times to isolate/mitigate if it is due to defective unit or if it is common "leakage" electric noise, I could further check if the unit is come with three-wire though they are using IEC outlet, in some instances, some may only terminate two-wire and leave the ground/earth "floating".

@mijostyn Thanks, I will check if it is DAC defect. I don't have any other DAC unfortunately.

Don't tolerate noise...keep at it until it's gone. I use a Bryston conditioner and various noise eliminating power supplies along with worsening deafness, although that last one I don't recommend although, hey, it works for me! What? What was that?