I think there are two issues in these discussions: 1- AC power cord with Rhodium or Gold Nema/IEC connectors and 2- Respectable AC outlet Rhodium or Gold.
Obviously, there is a relation between these two. In an exchange mail with Chris Vanhaul he mentioned that too, when I was hesitating to buy Rhodium Connector vs. Gold.
I need to say I dont have too much experience on different respectable ac outlets. I used to have a Hubbell Cryo and a Synergistic Research Teslaplex and I am happy with it. I am considering to add an Furutech GTX-D (R) in the near future, especially If I find a used one!!! There is a good review on enjoythemusic, January 2014, entitled: Audiophile AC Power Outlet Comparisons
Oyaide, Synergistic Teslaplex, ACME, Hubbell IG 5362, cruzeFIRST Audio Maestro, and Furutech GTX.
As for power cords, based on my own experiences. I think AC connectors play a big role on the output sound. Obviously, there are plenty parameters to consider too, like cable materials, no. of gauges, device equipment (CD player, DAc, preamp, AMP), power conditioner(s), the interconnect cables materials, speaker cables and most importantly the SPEAKERS. Devices being Tube based or Solid-State could also play a role in term of overall dynamic and revealing different frequency ranges. One could use Rhodium connector for CD player or preamp and Gold for Amps. For example, I use Dynamic Design power cord with Rhodium for one of my power conditioners feeding my LCD TV and AMP, CD player with an excellent clarity and results. The Dynamic Design Challenger cable with Gold connectors are used on my CD player. On my second system, I use a DD power cable with Rhodium feeding my preamp/processor.
I am afraid there is no any objective way to make rules on using Rhodium or Gold on CD player or amp. It is a multi-dimensional problem without any theoretical answer. The best way is to try and test.
Beyond all of these, THE MOST PROMINENT PARAMETER is the PERSONAL TASTE on type of music (Classic, chamber, Jazz, Blues, Rock, Metal), preference of being a bass freak or not, preference to have a more lively midrange, preference on more articulated vocal voices and enjoinment of hearing more pronounced instruments on high frequency or not.
I tested and have a lot of power cords and put some for sale. Some present an excellent sound especially with big orchestra and some are more suitable for jazz or chamber music. Of course, some cables present a reasonable compromise between the two. One might also choose to have entire power cords sets for each of these configuration. Some are very good for power conditioner, some are better for CD player or preamp or amps.
Regarding expensive power cords (>$800 used!), I am not sure, the subtle improvement that they might bring to your system could be really justifiable. I dont believe neither reviews on Magazines that could be biased. One could learn some notions from that but buying based on review is not recommended. Based on my experiences, buying a reasonable and not expensive cable and changing the nema/iec connectors would present a much better result. I think Rafael0054 did that too on his Purist audio cables.
Audiolabyrinth, Your Krell amp is a beast (in a good way) and I guess it comes with its own internally attached power cord. Have you ever considered to change that power cord and see what you get instead?! I was reading an interview with Dandagustino of Krell saying up to a few years ago he didnt believe on importance of Power cords! I guess it was the eras of before ~2004, where all these fancy/sophisticated Ac connectors didnt exist. Since then there has been more improvements and people pay more attentions on their connectors, not only Ac connectors but also interconnect and speaker cable connectors.