C.A.P.S v4 music server.

[Antoine]

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I am also pretty sure that there is a vast amount of b/s about this terrible electrical noise that PC's generate as if you apply this to the limit your Devialet cannot sound any good as they have switch mode PSU as well, but they are the quietest amps I have ever not heard, so someone some where is wrong.

I suppose I could be deaf but don't think so.

First I'm not trying to "convert" you in to a "believer" however your logic is a bit flawed IMHO. Devialet has designed it's own SMPS inside the Devialets. I'm quite sure they've done their best to minimize the effects of any noise into adjacent circuits through filtering and shielding. Anyone can see the shielding btw, the SMPS is encased in the black "tin" you see in pictures of the innards of a Devialet. Regular computers otoh are general purpose devices that only need to meet certain international EMI/RFI standards and these are of course no where near as high as those common in HiFi. I'm quite sure you have many times seen the ferrite beads in cables connected to computers and other devices like plasma TV's. These are mere band-aids to lower RFI emissions.

I have both an IT and EE background (not practicing EE) and while I used to be very skeptic about these kind of things I have actually learned a lot and also experienced the impact of RFI/EMI mitigating measures. The best examples of great pieces of engineering that combat the computer generated noise seeping in to our DAC/amplifier for me at the moment are the USB Regen and TotalDAC D1 USB Cable filter. I'd encourage any skeptic to try them if they use USB.

Ethernet AIR seems less susceptible to noise (I think mostly due to it's default galvanic isolation properties which is not there in USB). I've written before that IMO a standard PC with AIR sounds better than USB but one can get better SQ (with quite a wide margin) out of USB after optimizing the PC and USB output. You can't really explain this with pure computer science arguments alone. Most theorize it must be related to differences in the noise and distortion inducing properties of different hardware and even "software jitter". A recent theory for USB is that the amount of noise is of influence on the circuits guarding signal integrity. These circuits when fed more noise have to work harder to do their work creating more noise in the ground planes of the receiver. That noise is coupled into other parts of the receiving DAC and in our case amp.

Let's hope that new technologies/designer best practices will take away the need of a careful mitigation of noise and that we can tie our DAC's/amps to a computer just as "mindlessly" as a printer. Right now, computer audio is 'bleeding edge' at least for us audiophiles using consumer gear.