Does Gryphon Diablo 300 Benefit With A Costly Mains Power Cable?

Most amps will benefit with a Not Necessarily Pricey replacement power cord made for audio gear. You can find some on Amazon for under $100. I have five of them and they work well. If you examine their constructrion, you'll find they make the wires fit differently inside the insulation than ordinary, standard issue, power cords. The primary aim is to prevent the cable from picking up and conducting radio frequency signals into your equipment which was never designed to remove RF signals which might make it through the filters in the equipment designed to remove the AC frequency 50 - 60 Hz and nothng more. You wouldn't think stray radio signals would have any effect on audio gear, but they do. You may have noticed ads boasting frequency response flat to 1 or 2 MegaHz. That gear needs serious protection!  They don't have to be expensive. 

Does Gryphon Diablo 300 Benefit With A Costly Mains Power Cable?

In a word, no. Nor does any other component benefit objectively from a power cord, interconnect, etc.

Why, I wonder are premium amplifier manufacturers recently unable or unwilling to sell their VERY expensive product without adequate or perhaps matched power cords? 

Is that too much to ask of a $20,000 to $50,000+ amp? 

I smell a rat. 

@ryder I have gradually switched to Kimber on all components. 
I found the PK10 Ascent power cord on my Boulder 866 integrated amp to provide excellent power delivery and a very natural sound character without coloration or emphasis in any particular region. I never even once thought this power cord imparting any sonic trait on the presentation. It replaced nordost frey 2.  I then replaced one more nordost frey 2 on my Meitner DAC with a Kimber PK14 Ascent, again with the same results. I’m also using a PK14 Base on phono stage. Planning to upgrade to the Ascent soon. 
All other power cables I auditioned have colored the sound in some way. The coloration could work with some recordings and even some styles of music but at the end of the day you always notice it. 
Yes it’s all about synergy and preference. But if you are auditioning power cables, procure the Kimber. You might like it. Oh and another upside of these power cables…they’re extremely reasonably priced. 

Thanks @audphile1 useful to know. I’ll look at the Kimber PK10 Ascent power cord. Low price is surely useful and appealing to everyone. It’s just that most cheap is considered as not good, and it’s refreshing to know that some may deliver great results at a fraction of the price.