Anybody want a laugh?

Do some research and see the changes made. There may even be a video. It looked almost completely random and did not show any evidence of any engineering practice and certainly no testing to see if it worked other than the usual.


Than said, ... I thought I was cranky. I tip my hat :-)

CD318, the best is this for another product. Basically they figured out if you will fall for the marketing blurb of one, you will fall for connecting multiple in series and that you won’t question why the first one did not do the job.

Cumulative process – there is an increased level of Waversa Audio Processing when multiple WNDR capable units are connected, improving sound quality

On another note, and Ethernet connection is galvanically isolated. There is the potential for analog noise to be conducted over an Ethernet configuration and in a poorly designed DAC, I could foresee situations where it could cause an issue.  Of course you can also transmit 100 megabits per second across a fully isolated barrier for <$10 including support circuitry.

As a counter point djones51,  someone proved in a blind test with a significant group of audiophiles, that audiophiles couldn't tell when 2.5% distortion was added to their own system with their typical "listening" methods. On the other hand, in a controlled AB situation, engineers could pick up the difference quickly. It may be best to replace the term golden ears with gilded ears :-)

"Noise suppressing capacitors" as linked to in the article are not high grade capacitors. The only thing special about them is their failure mode.

This is not a "special" capacitor configuration. It is almost a given that the power supply in the Cisco switch already has it, as does most switch mode power supplies with a ground connection.

There are many ways to reduce and suppress this noise - installation methods, shielded cabling, filters, etc. One proven way in electronics design would be to replace lower-grade capacitors with noise suppressing capacitors. Here is an example of a capacitor design that reduces EMI/RFI and would have a measurable reductive effect on noise levels if installed into a Cisco switch:

https://www.illinoiscapacitor.com/pdf/Papers/EMI_RFI_suppression_capacitors.pdf

I can only assume you don't understand blind testing mahgister. The only requirement for blind testing is that you don't know what you are testing. That is it. That is all. You can take second, minutes, hours, days, months to review or make  change, the only requirement is you don't know what was changed.

My counter dougeyjones to the USB, is that the USB is competently designed and properly isolates the USB from the output including the potential to pass on EMI from the computer through the ground connection on the output to subsequent equipment. That even happens in lab equipment, let alone audio equipment. The higher

I have seen DACs in system drop from >100db SNR to <80db SNR and traced it back to the AC\DC supply in both desktops and laptops. I have seen SNR on USB powered lab ADCs go from <60db to >80db just by changing from wall powered to battery.  There is a very definite path for switching noise through EMI capacitors on the computer though the DAC into the pre-amp/amp more so with single ended audio connections and  3-wire equipment connections.

dougey, don't try to move the goal post. I don't know you qualifications, but you may want to lose the attitude. You haven't shown you are qualified to have one.

Testing methodology is literally real world, i.e. normal equipment configurations, as customers would have in their homes, using AP, or custom acquisition equipment to measure amplifier output gained back to the DAC in the first case with connected equipment, measuring both SNR and THD+N under computer loading, identifying issue and tracing back.  Line conditioning will not help unless the conditioning equipment has separately conditioned sections, and even then could be conditional on filter configuration. In both cases circuits were modified.

Second case is in the lab where we used a variety of NI and Labjack USB products for control and acquisition for automated testing. Quick experiments are often done with a laptop, and depending on the end equipment, even if transformer isolated, capacitive ground loops caused EMI that could be broken just by running off battery power.

If you are a electronics engineer, you probably have hooked a non-isolated USB debugger up to AC powered equipment (on the DC isolated side), and had connectivity issues due to noise. This is not a new phenomenon nor rocket science.

MSEE and about 15 years of pure electronics both at the board and semiconductor level, and then 15 years somewhat "involved", and almost as many in variety of acoustics.