When a power cord could obviously affect SQ

Once very skeptical myself, my logic was, standard home center wiring from the breaker box to the outlet, and that last 6 feet a miracle happens? I just couldn’t wrap my head around it. The a dealer said, take this home try it for a month, break in period, and if you don’t hear a difference, bring it back. How could I go wrong. Well I did not seem to notice any real difference, until I took it back. That night I was listening to the same music and I realized, something was missing. Bass had lost its definition, mid range was less pronounced, vocals seemed to have a more brashness. Music I had never noticed these things, was not as enjoyable as they had been.

So now came the question, what about other brands. I contacted the Cable Company and asked for their recommendations. I requested 3 samples in my price range from their lending library and narrowed it down to the same cable the dealer had let me use. I won’t mention the brand or model to avoid that debate. But I have standardized on the brand for all my cables, since I do believe there is a synergy when one brand is used. Plus I had already settled on them for my interconnects.

So I recommend you contact the Cable Company and get their advice and try some from their lending library. 

I guess it is all in the word could.  I'd be more interested in does.  As in "When a power cord could does obviously affect SQ".

Although I have documented a case where adding ferrite chokes to a manufacturer's power cord solved a digital interference problem, in general I am not really convinced - except that the margin on power cables is so high, there is a strong business case for the dealer to push them 

I recently bought a SoulNote phono / equaliser which came with manufacturer's instructions to only use the supplied power cable. Unfortunately it did not have an Australian plug.  Catch 22.

If power cables really do make a difference, I believe it is because they mitigate EFI coming from the component, rather than from the last six feet of the mains. At least for 240-V mains in a non-industrial area ...

Frank Ng is a master with tube amps! I have one of his 2A3 EVO integrated amps with tubes and cables he recommended and the sound it produces is spectacular. It revivals my reference system at a fraction of the cost. Take his advice and run with it, you will not be disappointed.

@retiredaudioguy - simply ask Frank Ng what he suggest using with his amps. Also, the lower the noise floor, the more you’ll notice differences. Generally, tube amps are typically noisier that SS at lower price points, but tube noise floor can be lowered significantly but usually at a higher cost like some Zesto or Audio Research offerings. 

Does the manufacturer include the cables in the base cost of the amps or is it extra? That is the best test of how much he believes they really improve the sound.