Does this only happen with USB audio devices? I have a Fiio E17k Alpen and while I've never had issues with the PSU making it whine (I have a Seasonic PSU,) but, I did actually have issues with which USB port I plugged it into. You mentioned that you isolated USB power from the device and it still occurred. That's weird. First of all, if power was isolated, any "noise" on the data lines would disrupt the digital USB signal which would cause the device to disconnect. When it comes to differential signaling, if there is an uncorrectable error, it will just fall over. It also would require one of the data lines not being balanced with the other (meaning that one of the differential pairs is getting different interference than the other because differential signaling depends on interference between the two being the same to do error correction.)
Perhaps I'm getting ahead of myself to assume that not running off of bus power is the same as isolating from the usb power bus. Obviously it's still used for general operation. I know the ground still comes into play, at least. Cut that, even on a signal carrying only data and what you describe happens, eventually - though the noise drops away lol. Ask me how I know
When I say that I'm isolating from USB power, I'm meaning the device isn't powered directly by the power bus, not that it's necessarily not connected to the power bus. It's just running off of its own power supply. In all of my experiences here, every form of interference I encountered was not present in devices that natively ran on their own dedicated power supplies - the source of the noise was there, but they simply did not care.
Though interestingly enough, trying to inject a cleaner power signal via something like a Schiit Wyrd (negates power from bus and swaps for 5v from LPS) or adapters that allow you to feed dedicated power from a SMPS, the noise would still be present. Basically fully dedicated mains = no noise. Power through the USB cable itself, whether straight from bus, or through injection from dedicated power supply = noise. So if it took any kind of power through the USB port, it was noisy.
Does that make more sense? From this, I assume it's something on the ground path, internally - and only when the cable is carrying power. Only thing it could be really. Though in my case, no ground loop isolator had any effect. Seems it's something inherent to how USB carries data that allows this particular form of interference to get through.
And no it wasn't just the USB... ...mobo analog outputs were affected as well, just not nearly as much. The only output not affected at all was the toslink.
Now, with that said, if my USB audio device connects to a USB 3.0 port, for some weird reason it will produce an insane amount of static rendering it practically unusable and after days of research, it turned out to be the usage of one of the USB 3.0 ports on my board. Putting it in a USB 2.0 port or behind a USB 2.0 hub on a 3.0 port solved the issue for me. What's even more weird is that I can plug it into a USB 3.0 port on my Macbook Pro and it works, so not only was it USB 3.0, it was USB 3.0 in the context of my tower.
It also seems to be the case that many USB audio devices are sensitive to being put on a USB 3.0 port so, if this issue comes back up, I would focus on that.
I've noticed this in the past, but in this case it wasn't static, but intense ringing. Seems like I had a different problem. All ports were the same for me - just didn't matter. Front, rear, 2.0, 3.0, 3.1...
And now that it's fixed, I can use 3.0 or even 3.1 with no issues, though it's a 2.0 device, so I use a 2.0 port.
FWIW, I've had my Seasonic 1000w Platinum for > 6 years and it has been rock solid and I've bought Seasonic X-series gold PSUs for several other people, none of which have had an issue with coil whine or failures but, I have definitely had issues with my USB audio device due to the controller being used or OS (not quite sure which it was.)
Haha, I believe it! On both fronts. In my case the only reason I knew it was the PSU was because the noise coming directly out of the PSU was the same as the noise coming out of my speakers! I don't think that's normal or even all that common!
btw I have some usb audio equipment, i'll be very disappointed if theres a problem. I havnt had chance to have a jam since I set up this psu but to think of it, I always had to play around with cables to get perfect silence on the line. I never thought it could be the quality of the power being fed the motherboard..
If there's anything this has solidified for me, it's that USB audio sucks. In the future I'll be avoiding it any way I can. USB was never made for audio, it just kinda sorta works... ...mostly. The biggest mistake I think these companies marketing their USB-powered recording interfaces as professional equipment made was assuming that most computers are a quiet, stable source of power. Most of the noise problems I see are with USB interfaces and mics hooked up to a noisy computer. Generally they work okay, but man, when they don't...
Next time, I'm just gonna throw down and go full toslink. Biggest pain in my ass for something so simple. I thought toslink would be a hassle to setup, but at least it would've been foolproof.
In general, power is everything with audio. If the power going in has issues, they're gonna carry through. So to me it makes sense that a PSU could introduce noise into audio systems. A little suprised that it carried through digital signals, though. DACs and ADCs have no way to take interference and convert it to a digital signal 1:1. That'd be some real voodoo. I always thought noise was limited to analog because of that. Digital is supposed to be either good or dead. What happened to me is something akin to if you saw static on your HDMI display.
*shrugs* Not much you can do except get that straightened out. Though, I'd say chances are if your PSU is running quiet right now, you'll probably be fine. Like I said, in my case there was loud, audible noise coming from the PSU as well.
