I took delivery of a Zu Bok about two weeks ago, gave it due play time and then tried it. It definitely made a difference, a noticeable and substantial difference - enough difference that I find annoying and it's going back.
I don't get why some "engineers" (i.e. someone with a college degree in ____ engineering?) often put down the difference PC's can make. Instead of behaving like true scientists inspired by curiosity they can't wait to put power cables down, admittedly often either for lack of experience with PC's or scientific proof (prejudice?) that PC's can make a difference.
Placebo effect. Without actual testing as to how power cords could make such a difference, we're forced to rely only on subjective evidence. Given how differently two people can hear the same set of headphones - one might think the highs were shrill and the bass overwhelming, while another finds the highs just right and the bass a good level - it's very hard to be able to objectively say whether they do make a difference, and if so, how much of a difference they do.
Also, remember that engineers aren't scientists. Quite a few engineers absolutely HATE dealing with new things. Most of them prefer using the tested, standard stuff, and have a rather powerful dislike for new things. Honestly, when you think about it, power cables making as much of a difference as some people claim seems absurd - see my thoughts on how the power gets to the cord as to why. Conversely, you have people who A/B test the cords and say they hear a very large difference. We have logic saying that these cables shouldn't really make such a difference, and then we have personal accounts saying they do.
Another thing to remember is that a lot of engineers are conservative cynics. Until they can actually test something themselves, they're not going to have any good reason to agree that it makes a difference, especially as common logic says it shouldn't. Now granted, if someone is going to hold a strong opinion about a subject, especially one as subjective as this, they really should test things themselves, but that doesn't always happen.
I think the biggest issue at hand is WHY power cables could possibly make such a large difference. Ostensibly, if the main power cable makes such a difference, then one should also be able to garner such changes by using different wiring inside the amp itself. Likewise, switching the power outlet out should cause a change on the sound. Again, changing the wiring that runs from the main junction box to the outlet everything is plugged in to should change the sound. What we really need, and I don't think it's been done, is for someone to actually do each of these steps. Listen to an absolute stock amp and record their opinions. Change the internal wiring, record any differences they heard. Change the power cord, record differences. Change outlet, record differences. Change wiring from outlet to junction box, record differences. It would be even better for multiple people - a sample size of 10 might work, although the experimental psychologist in me calls for a much broader cross-section utilizing both audiophiles and non-audiophiles, as well as people of different ages and races - to record their opinions at each step on the experiment. This could be done utilizing various headphones, also - use 5 different headphones with varied impedance and sensitivity.
However, such an experiment wouldn't be cheap, nor particularly easy for the average person to set up. Given that, I don't think it's reasonable to expect any cessation on the opinion war on power cables at any point in the future.