When a power cord could obviously affect SQ

@retiredaudioguy   What brand/make power cable has Frank supplied?  If it is beyond the  basic generic cable that Triode normally supplies (I have a Finale Audio integrated) than it would seem that he has answered your SQ question on this specific amp

There may be a tube directly connected to the transformer,  but that tube must be a rectifier.  It’s not a magically sensitive amp.  AC must get to DC before the signal amplifying devices touch it. 

Now, what IS magic are the tube amps that have no output transformer or caps and drive ESL’s directly.  That is pretty cool. 

@cruising44 

FYI, it may take for ever to burn-in/break-in a power cord by just using a piece of audio equipment to burn it in. Especially a piece of low powered equipment like a DAC, transport, or even most SS preamps.

What works great is to use refrigerator or a dehumidifier. You will need to buy a NEMA 5-15R to IEC C14 adapter. 

Plug the power cord into the wall power outlet. Install the adapter to IEC female connector on the power cord. Plug the refrigerator into the adapter. Leave the power cord connected to the refrigerator  for 4 or 5 days. 

Example of the NEMA 5-15R to IEC C14 adapter:

https://tripplite.eaton.com/nema-5-15r-to-c14-adapter-10a-125v-black~P002000 

As for this:

He also recommended a power outlet that the Hospitals use as a foundation which will grip the plug without fail.

You have to be careful what you buy today. Most hospital Grade duplex receptacle outlets made today have a galvanized steel supporting back strap. Bad for the sound of audio equipment plugged into it. That includes Hubbell.

FWIW, you can buy an extra heavy duty commercial/industrial grade duplex outlet that has the same contacts and body as the hospital grade outlet minus the green dot and a beefed up ground contact. And you can find one that will not have a galvanized steel supporting back strap. 

Look for an outlet that has not nickel plated brass contacts and a non nickel plated brass back strap. 

Going from stock cords on my power amps to heavier gauge/better insulated cords made an audible difference. Replacing the stock cords on my Streamer, DAC and Preamp also made a difference, just not as dramatic.

My experience.

Just recently while running 5Hz - 3500 MHz sweeps using a field strength instrument, I noted substantial differences in radiated EMI from various audio power cables. Some emitted surprisingly strong magnetic fields that radiated well beyond the cable jacket, whereas others had undetectable emissions. This implies some cables are clearly better suited for use in close proximity with sensitive digital components (e.g. DACs and streamers) and interconnects.

From an internal perspective, a power cable is not a one-way street, and the better way to view it is not as the last few feet of power feed, but rather as first few feet of what the component "sees" when propagating away problematic internal noise generated by the component itself. This noise exerts direct influence on audio performance, and cable characteristics determine how efficiently it is removed. When one views it from this perspective, it's not a stretch to understand why power cables can "sound" different.