Is there a minimum length for power cords?

... any length shorter than 1.8 meters (5.9 feet)will begin to degrade the effectiveness of the shielding and filtering capabilities; regardless of who is the manufacturer.

But on the other hand the resistance and inductance of the cord will increase in proportion to its length. Both of those increases can have adverse sonic consequences if large enough.

Personally, however, assuming adequate gauge for the application and assuming cord designs that are identical aside from length I suspect that in most and perhaps just about all systems none of these factors are likely to be great enough to make an audible difference for lengths of up to 8 or 10 feet or so, and perhaps more.

And to prove otherwise would require, as I see it, performing comparisons between different lengths of identical cords that are repeated multiple times, going back and forth between the two lengths to assure that the results are consistent and that perceived differences are not the result of extraneous variables or misperception. I doubt that very many audiophiles have done that, and even if some have I see no reason to expect their results to be applicable to different components, system configurations, and AC characteristics.

Regards,
-- Al

The unnamed manufacturer is LAT International. Found it with a quick search on part of the quote.

Yes, the manufacturer I referred to is LAT International.

my posts do not seemed to be getting posted???

Here in New Zealand the power outlets within a house are configured in a loop. If a power cable is attached to the loop and it is shorter than 2 metres then it will be seen by the power supply as part of the loop. If the power cable is 2 metres or more, then it will be seen as a spur rather than part of a loop, and the electrical behaviour will be different.
If you have a dedicated mains supply - and you are running a spur from the main power distribution board, then you have created a spur and the length of power cable may be less important in this regard.