Another unconventional power cord test?

You're right John, this can be frustrating! What's even more puzzling is the fact that if I don't like the sound I'll reboot my computer and refresh the room correction software and the sound is better. So weird, and almost silly. I typically make that part of the experience: reboot and relaunch correction software each time I engage in a listening session. Better safe than sorry.

In terms of isolating the PC, plugging the power cord into a different circuit is totally necessary. Getting it to run on battery is even better, not very convenient though.

I don't typically buy in to very expensive cables but I did buy a Wireworld Ultraviolet for my usb to Dac connection. I am not spending $1000 for the Light Harmonic USB cable, even if it does make your morning coffee!

I've taken it a few steps further by incorporating a USB to SPDIF converter that supplies power to the converter with a battery. So i've completely isolated the sensitive clocks in the converter from computer noise.

Taken together it sounds great. Now, i mentioned room correction software - i'm using the ARC system 2 - and the difference is astounding. I can't listen anymore unless the software is engaged. Had I known this in the past I would have hung on to my old Adcom amps and most of my other components since the room correction makes the MOST difference I've ever heard in one component. I've verified all this with many test subjects. Nobody can hear a powercord difference, everyone can hear room correction difference. And ARC 2 is cheaper than a single high end powercord - at least it was!

I use Jriver 16 - too scared to update since everything works now, no point in ruining that! But I have the software load 10 seconds of data into RAM - prebuffer - to add stability to the data output. I have no idea what difference this makes to the big picture but prebuffering prevents any issues related to the computer itself taking resources away from streaming that data. Even though I'm using the preferred asynchronous USB protocol it makes sense to prebuffer.

I’ve had the problems in even believing in the theory that PCs do make a difference. Then I’ve tried to build one,and it sounded way better then 2$/piece power cords I’ve had until then.
Tried a better version, it was even better sounding. Built a few versions, improved the design, and got the idea of "what changes and improves the sound in a which way"...
Now I’m on the end of a journey, using only OCC copper and best quality connectors.
The change in my system is dramatic, also in my office system.

Filtering and blocking noise from one device to another is done by few power conditioners, most just hook the sockets in parallel, a design choice but IME not a good one. Audience adept Response have all filters in each socket just to avoid electrosmog pollution.

As for good sound from PC, there are tons of advice on CA. Free and certainly worth a look is the Fidelizer tool. IME, best bang for the buck is to have first a good USB bridge between PC and DAC, Supra (hand made) USB cables are great value/money, power supply of your DAC is crucial, there are plenty LPS around to feed the little monster. USB noise harvesters et al can help. The UpTone Regen is a must for mid-fi DAC and up.

Back to PC, best bang/buck is a dedicated line, then comes the AC wall sockets. Evaluating PC can be addictive and one has to be careful not to end up with more worth in cabling than gear so a regular sanity check helps. For my second system, I was not aware that I drifted up to nearly 60% for power conditioning and all cabling in terms of total value of the system until I did a tally and keep now everything in a spreadsheet per doctor's orders. 

Thank goodness the linestage I am using currently has a captive cord.  One less thing to improve on!  Or should I say worry about.  I have tried about a dozen PC's and most offer an improvement or change of some sort.  The characteristic I listen for the most is a relaxing or smoothing out the presentation.  That gives me long term acceptance/enjoyment.

I agree with Jazz, I have had dedicated lines for a while and that was a noticeable improvement, darker background and a relaxing nature.  That is why I look for that in a power cord.  Also, I am embarrassed to say what I will spend on an interconnect - I just do not have that same feeling with a PC.  I can't get my head around it.  For example, my phono stage has a separate power supply connected with a captive power cord.  I cannot tell a difference between any PC I have tried in that spot.  The reluctance to spend big bucks on PC's has probably saved me thousands, but regrettably have spent it on IC's or SC's.  That's another subject but I have burned through more than a dozen of those!

Pops, as always, design matters and PC won't make (much of)  a different if the design is excellent. You have probably a such a linestage.
Indeed I have noticed with some great power amps (e.g. Jeff Rowland) that there is little the PC can influence but with most not-so-expensive or well designed gear the PC does influence the characteristic quite a bit.

With IC, another important factor is the impedance matching between the source and destination device that comes into the equation so there is not just about metallurgy, isolation, skin effect, etc. Lately I have spent a fortune on cables with magnets (too much talk already on this forum), they are indeed transformative and addictive. The question begs - and John is spot on here - if I can achieve the same result with other components. I have been longing for a one box solution like the Devialet so finally can get rid of those expensive accessories but am afraid my old ears are used to (those lush sounding) tubes. Maybe those ingenious French buys will add an option for an iFi iTube type module. 

In fact, all cabling matters (don't forget the fuses!).

Sometimes we forget to listen to the music (our better halves will remind us of that) but the kid inside us wants to venture onwards....