Can upgraded power cords help my setup?

I just use Zu audio Birth cables that I purchased from Ebay store that I use with Kef LS 50W cant tell much of a diffidence the stock cables supplied by Kef also seem to be of good quality

NO.

Power cords do absolutely nothing.  Think about it, what do you think you are plugged into?  As long as you are delivering the volts and amperes you are done.

All audio equipment runs on DC.  So what does matter is if your power supplies in your equipment is doing a good job of converting AC to DC.

Agree with David Clarke 100%. Power cords will do nothing. Instead of wasting money on expensive cables, buy a good book about electronics and learn it. It will send you tons of money in the future, because you will see through audiowoo.

David and Mr Kaic,

I invite you to come listen to my system, a moderately high end system and see if you can determine (blindly) when expensive power cords are being used and when they are not.
Everyone that has listened easily determined when the expensive power cords were being used - and many of these listeners weren't audiophiles, just "regular" people who easily heard the difference.
And the "difference" was a dramatic improvement - again, easily recognized.
Here's a link to a past post I contributed to regarding power cords:
https://forum.audiogon.com/discussions/still-mystified-by-mega-expensive-power-cords
And here's my past power cord contribution pasted:

I'd like to explain why power cords are important. I�ll be using a minimum of technical terms and I�d like to over simplify things � so we can identify what is really important. Please realize I�ll explain things without being too detailed � using simple assumptions to make getting to our conclusion easier. So please don�t reply and invalidate something said � I�ll ask everyone to follow along to the end.

For the record, I have an engineering degree � but I will humbly state there are MANY individuals who know SIGNIFICANTLY more than I do. 

Here goes;

Power stations generate electricity and distributed it through miles of power lines, switching stations and transformers. These power lines, switching stations and transformers are called the power grid. Relatively to our audiophile use, electricity traveling through the power grid gets SEVERLY contaminated. In this instance, contaminated means the electricity is no longer pure, but has many other parts or components in it that cause problems. 

Many things using electricity can crudely filter out some of the contamination and / or operate without removing the contamination without a problem. Simple on / off electrical motors (like attic fan motors) are a great example, and operate fine using contaminated or �dirty� power. 

Oversimplified, electronic equipment is more sensitive to contamination and requires more filtering � and digital electrical equipment is the most sensitive and requires the most filtering. 

How does the electrical power become contaminated?

The electrical power grid�s power lines act like antennas and experience Radio Frequency (RF) and Electro Magnetic Induction Interference (EMI) and these are two things that contaminate the electricity. This contamination becomes significant over the many miles of a power grid. This contamination also occurs in our house.

Electricity also becomes contaminated from electrical devices within the house. Light dimmers are a good example � a light dimmer being used in a house can contaminate the electricity within the house. The same goes for the neighbors in your community, especially commercial and sometimes industrial neighbors. 

So, now that we�ve explained how we have contaminated power at the plug we use for our stereo � how do we fix the problem? Power conditioners and / or power cords.

Power conditioners seem obvious but designing and building one to perform well is tricky � very tricky! The same can be said for power cords.

First, we�ll need to understand a few things about electricity to understand how and why power cords will or won�t work well. To keep things simpler, we won�t consider the metallurgy, configuration and insulation of wire and plug.

The job of the power cord is to deliver power. In theory, a perfect power cord will eliminate all the contamination and the worst possible power cord will add more contamination to the electricity it delivers.

A perfect power cord will use wire and plugs that are designed and constructed to eliminate contamination (in our example Radio Frequency and Electro Magnetic Induction contamination and contamination from within one�s own house). Doing so isn�t impossible � it just requires applying proven scientific principals and being able to identify and measure the specific parameters that are critical to eliminating the contamination so pure electricity can be fed to our audiophile equipment. It also requires repeated iterations and testing of a design until the desired performance is obtained. The finished power cord product allows electronic equipment (especially digital electronic equipment) to operate at peak performance.

Many people consider the ability of the wire to deliver a larger amount of current, which leads to the �bigger is better� mantra or �size does matter� view, but this is only one role of the power cord. Providing LOTS of contaminated power isn�t what we want. Providing reasonably more pure power than necessary is what we desire, and is exactly what a quality power cord is designed to do.

Creating a good performing power cord is reasonably easy. As we strive to improve performance further, more issues become critical � and executing each successive stage becomes more difficult, complex and expensive. Periodically, technology makes leap advancements, sometimes cost effectively � which result in a significant performance improvement becoming available to more people.

Similar to other commodities, our audiophile industry has a point where spending more yields significantly better performance. Continuing to ascend the performance ladder, becoming more difficult, complex and expensive � yields further incremental gains. The law of diminishing returns applies and there�s usually a price / performance point that provides exceptional performance at an �acceptable� expense. At the pinnacle of performance, subtle gains may be extremely expensive yet make the dramatic difference in the illusion (of a real performance) we strive to create.

Technically, how does a power cord provide pure power? Explaining the many parts of a well designed and constructed power cord requires a good technical understanding of electricity, metallurgy, dielectrics, electro-magnetics and physics. Power cord design and construction become critical for premium performance � which are topics for other discussions.

So when someone asks why power cords sound different, you now have a conceptual understanding of why � and can realize it�s not �snake oil.� I hope I�ve allowed everyone to realize why power cords make a difference.

Music is a profound part of my life, and I�ve been involved in our audiophile industry for more than 20 years, and I�m involved in it solely for the love of music. I will be creating a website addressing these and other issues and will invite anyone interested to visit once it�s operational.

Kindest regards, Thomas Foti

The AC 14SE MKII !    Those are class D amps in the Kefs. .

The AC 9SE MKII's are for high current, high power, analog amps.  You'd be surprised how Class D will save you on your electrical bill. I tried the 9's on a regular powered amp and it did not sound as good as the 14's.