Hardware

They’re generally much less noisy than a PC.

I had chronic problems with my phone injecting sound into the analog output that I was feeding into my car stereo AUX input when I was charging the phone. Eventually plugged a Bluetooth receiver that had a power supply that didn't have the problem into the AUX jack, and took the slightly-ludicrous approach of wirelessly-transmitting the signal a foot or so over Bluetooth to get off my phone's DAC.

The phone was fine as long as it wasn't charging, though.

Some years back, when I was more-interested in analog headphones amplifiers, I discovered that there is

or was, out of date here

something of a convention of people running them powered off plain ol' 9V batteries to cut any external source of noise from the power source. That's more effort than I'm willing to go to

and frankly, for what these sorts of people are paying for analog headphones amplifiers, I'd expect some kind of reasonable power supply in the amplifier that can filter noise out

but I wouldn't be surprised if there are still people doing something like that.

Using powered USB hubs is another way to influence this on a USB bus, get a different source of (hopefully less dirty, especially if there are no other consumers) power into the equation.

I do have one analog mixer that only drew power from the USB bus, isn't a DAC, didn't use the USB bus for data. That again had a power supply that leaked audible

and I'm not talking "audiophile edge of hearing stuff", as I'm not all that picky, but really irritating

noise from the USB bus into the mixed audio. In that case, I had success just yanking it off my computer's USB tree and stuffing it onto a dedicated USB wall charger that was a quiet enough source of power that I, at least, couldn't hear anything.

The pro audio world also has something of a tradition of barrel connectors for power, in my limited experience. There are pro or semi-pro DACs -- and I think that both of my Behringer USB DACs can do this

that can draw power from a USB power supply, but if you feed them 9V or whatever from a barrel connector will use that as their source instead.

I'm not near the thing, but lemme check Amazon.

looks

Yeah. Has a 9V barrel input, so you can put the device on a dedicated DC power source.

That way, even if you're using the USB bus as a feed for digital data for your DAC, you aren't bound to dealing with noise off the USB power. My experience was that the power circuitry on those things is already capable of filtering out the USB power noise (at least to the level that I don't notice it by ear, which may not be the highest bar), so I never bothered with a separate DC power source.