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[PrinterPrinter]

Hello people,
My Stereo PC is based around a Streacom chassis with their Nano PSU - I read it's incredibly noisy RF-wise and that a linear PSU would make an audible improvement.

Has anyone done it? Would it make an improvement?
My DAC is currently connected to the PC via Optical - would a noisy PSU influence it?

Can anyone recommend a 3rd party linear PSU? I understand I need to replace the 'power brick' - outside the computer, not the part inside.

[JimH]

My DAC is currently connected to the PC via Optical - would a noisy PSU influence it?

No.  It's not possible, although some will say otherwise.

[PrinterPrinter]

So there's no chance noise the the PSU could make JRiver render some music 'wrongly'...?

[mwillems]

If noisy PSUs were causing actual software processing errors, nothing in PCs would work (not the OS, not audio, nothing).  The more usual concern is that electrical noise from the PC can sometimes affect a poorly insulated DAC when the two share an electrical connection.  

But with an optical connection and a quality DAC, I don't think it's possible that a noisy PSU could make any meaningful difference.  An optical digital connection does not electrically link the PC to the DAC, so there can't be direct electrical hum or interference from a noisy PSU.

A hostile electrical environment in the source PC can (at least theoretically) create timing errors (called jitter), but there are two things to consider:

a) There doesn't seem to be much hard evidence (to include measurements) that noisy PSUs inside modern PCs actually cause meaningful (meaning audible) increases in jitter (over the baseline jitter that would be caused by operating a PC with any PSU).  There are papers documenting the issue generally and a few blog/forum posts by DAC designers talking in very abstract terms, but not much by way of measurement on modern equipment (the only measurements on this specific issue that I've seen were in some AES papers from the 90's).  To be clear, jitter is real and measurable, and can be audible, but it's not necessarily easy to hear, and it's not clear that noisy PSUs in modern equipment affect digital outputs (like TOSLINK) in any meaningful way, or that a linear supply would be any better. There may well be a measurable effect, but it won't likely be an audible one. But none of that matters very much because:

b) Decent modern DACs are highly resistant to jitter, so if it concerns you, just make sure to find a DAC that has solid (measured) jitter rejection performance.  A DAC with 110dB of jitter rejection and an optical connection simply doesn't care what your PC is doing in any meaningful way.

Here's a good article on the issue, with measurements of a few differently priced DACs: http://nwavguy.blogspot.com/2011/02/jitter-does-it-matter.html.

[PrinterPrinter]

Thanks mate!

And if the computer and DAC were connected by USB? a noisy PSU would have a greater impact?

[mwillems]

I have encountered USB DACs that misbehave due to electrical interference from the PC, but the majority of them have been models that draw their power from the same USB port they're using to communicate with the PC.  So the USB port is not only transmitting data, but also power, and in that circumstance it requires much better design to make the DAC resistant to EMI from the PC.  I've had USB-powered DACs that didn't seem to care, but I've definitely had some that picked up noise from PCs or USB3 ports (in particular).  If your external DAC has a dedicated power source, the DAC is much less likely to be susceptible to PC EMI.

Bottom line: some USB-powered DACs do misbehave, but I'm not sure that a linear power supply will improve that situation (it's just bad DAC design generally, or USB3 interference, which is unfixable).  I haven't personally used a DAC with a dedicated power source that seemed to pick up any meaningful EMI from a PC.

[astromo]

I was using a Dragonfly and then I upgraded to AudioEngine D1 24-bit DAC for my machine at work and I a rice bubbles audio experience for both bits of hardware - yep .. snap, crackle and pop.

Got one of these:
http://hifimediy.com/usb-isolator
Hassles sorted. May not suit everyone because it's limited to 96kHz but it's a low risk punt if it suits otherwise.