It’s the EHX pedals. I have a dozen pedals of all types, 9 and 12vs, and I can plug them all in using my pedal power-style adapters, and there is no signal noise (of course you get extra sound from the pedals in some cases, but this is just increased in white noise, or swirling if you have a flanger or phaser turned on or something. Totally different thing, and you can turn it off by turning the pedal off. Then when you plug in any of my EHX pedals, you get a whirling electronic pattern (kind of a highpitched current-y sound), which you can’t remove.
I don’t think I’m the only one dealing with this, as the guy at my local music shop seemed familiar with the EHX pedal noise problem as well. And it’s clearly demonstrable with any of my multi-power bars.
I suspect it’s because EHX uses the 9.6, but it could be some other issue with them as well.
Hopefully someone will have figured something out.