Can a power cord increase the resolution of an Class D (SMPS) amp by more than 5% ?

I compared a small handful of upgraded cables in the $300-$350 range. Compared them to the stock cables that came with my equipment, I got varied results from no improvement, to a small improvement, to slightly worse sound. The differences I heard with these cables in my system was mostly in the upper bass range. Obviously the cables with the heavier upper bass made some of the lower mids sound ever so slightly veiled. I found one cable of the bunch to give me a very clean sounding upper bass which in turn gave a tiny improvement in the mids. Granted all these differences were extremely small, but I felt if I could hear a difference so it wouldn't hurt to  use them, right?  It took a week of going back and forth with these cables and was quite the tedious process. I would like to think I made an informed decision, and it would be money well spent. The cable I chose at the time was $325 new for a 6 ft. length. I found several  more of these cables used on Audiogon in a range of $120 to $150 each, so I bought them to wire my entire system. I do like the result, but I don't think I would buy mega buck power cords. IMO. 

I have a Class D hybrid integrated amp with Hypex-400 modules.

No, unless you want it to...

I’m having trouble seeing how a power cord could make a difference.  After all, the stock cable should be capable of delivering the full mains power available to the amp, and the power supply on the amp is going to clean up any minor amount of interference that could possibly sneak in between the wall and the unit.  

Besides, if it was easy to greatly increase the performance of an Amp with a different power cord, why wouldn’t they just ship it with a different power cord?  Why handicap yourself is there’s such an easy solution?   

tutetibiimperes,

I know and understand why a lot of people feel power cords are just so much "snake oil". If you ever get a chance to try a few, well give it a whirl. Just keep an open mind and listen closely. You might be surprised. Maybe.....