Help :( Speakers making constant static sound I cannot figure it out

Speaker "whooshing" static sound

Other system setup photos for reference

So I linked to the video of the sound for reference.  It's been driving me crazy, so today I unplugged everything, took it all away from the console, cleaned it all nicely, and the plan was to, one by one, re-attach each component until the static returned, to try and isolate the cause.

Well, the only thing plugged in is the amp (Rogue Cronus magnum iii) and speakers (Focal Kanta 3), and the static is back.  It is a constant sound, there is no source plugged in, and the sound does not fluctuate at all when I turn the volume up or down, or turn the knob to change source, or even when I turn the balance all the way left or right, it seems to have nothing to do with the amp settings then, so where could it even be coming from?  I just checked the power tube bias and all 4 looked perfect.

TV is also unplugged, so there's nothing around to be causing feedback or rf interference that I can think of.

I don't have any other speaker cables to test against but did swap power cords between some components.  All cabling throughout is Nordost Heimdall 2, and is running through the Nordost QBase power distributor which has 1 each of the QK1 and QV2 plugged into it.  Main cable from the QBase to the wall is Shunyata as I needed a 20amp cord to work with that box and there isn't one in the Heimdall line.  Wall receptacle is a 20amp one that I installed (can't recall the make at the moment, but I believe I got it from a user on here some years ago.)

However, I tried skipping the QBase and plugging the amp straight into that wall outlet, no change.  Then I tried plugging it straight into a different outlet, still no change.

Based on the the type of sound heard in the linked video, and the details that it seems totally unaffected by volume, balance, source selection, etc., what do you think it could be?  Does it seem likely to be an issue with the speakers, speaker cables, or the amp?  At least that would narrow down how to address it.

Thanks for any helpful suggestions.