I found the source of the noise.
I have made a video comparing HDMI vs Analog.
https://youtu.be/7vfPUiGABwI
I tried out different settings.
And ultimately at the end of the video different audio processing options of the denon 1909 receiver.
For some strange reason audio processing is not available for the analog inputs, perhaps this is because HDMI is connected, when HDMI is disconnected maybe audio processing will become available again, not sure about that, will have to do a seperate test of that. (I will check manual too about this might be mentioned).
Anyway at the end of the video when playing around with last ninja music right before I switch to it I notice the "noise" on the speakers. It's maybe not hearable on the video unless maybe setting volume to max, but I do not recommend it for now, I may have to make a new video about this particular noise.
In the video at 13:36 and 13:40 you can see me switching to HDMI/HDP mode and that's when I notice the noise on the speakers (slightly).
I say: "Yeah"
(If you download video try playing it with windows media player, it's a bit faster than vcl media player for playing on low end systems).
I think I now know what/where this noise is coming from.
To re-produce the following steps have to be taken:
1. Switch to HDMI/HDP input
2. Have Auddyssey processing on
3. Have Dynamic EQ/Volume on.
What these "audio processing functions" do is:
They enhance "low volume sounds" which can be very cool especially in combination with 7 CH stereo for games like Warcraft Frozen Throne.
The AL/DirectX 3D sound positioning of the camera high above the battlefield will cause soft sounds like footsteps of soldiers or magic spells or creatures to be very soft/distant and basically not hearable on surround sound systems, maybe even stereo too.
What this denon 1909 receiver processing does, especially if in 7 ch stereo mode:
1. 7 ch stereo mode plays steroe on all channels, especiall sides and rear both basically.
2. The auddyssey processing and dynamic eq/volume further enhance low volume sounds and tune down high volume sounds.
So basically what is happening is:
Where there is no sound playing... apperently there is still a little bit of sound somewhere in the system... some voltages or signal might still be coming in over hdmi...
Maybe just sound from the universe or something.
And auddyssey/dynamic eq/volume picks up on this signal... maybe through fourrier transform techniques.
Or perhaps it's simply enhancing the noise in the denon receiver itself.
Somehow it's detecting a faint noise and basically boosting/enhancing it... which is ofcourse kinda weird.
Reminds me of tape casette decks and playing empty casette tape or something and basically playing noise ?!
Well that's my explanation at least for now.
Though I could do some further experimentation with this auddyssey and dynamic eq/volume and try and see what kind of noise this is by setting the volume really high.
Maybe it will pick up something interesting, ofcourse I shouldn't play any sound otherwise my ears getting blasted =D
Well at least this solves the mystery a little bit and I am not getting closer to solving/digging deeper into this mystery ! =D LOL.
Bye for now,
Skybuck.