After all this talk about mains cables, I decided to try it myself, after all, how could 1m of fancy cable make a difference in the many Kilometres of cable leading up to my house?
If it did not work, I could send it back.

Well, I am almost embarrassed to say it's still here. Many of you will now be laughing, but hey it's my money and it is my ears/brain combination that are telling me that the system is better with it feeding my mains regenerator.
I can't tell you how or why, and I don't really care.

To start my experiment I contracted Mr MCRU, as I am sure he would have something suitable for my budget, and some advice to offer. He has always been down to earth and offered me good honest advice.
He sent me a chunky metre long cable fitted with a Furutech FI-E11 copper Schuko plug, and a FURUTECH FI-11 copper IEC connector. The cable itself is (probably) the Neotech NEP-3001 III UP-OCC cable. As I am sure you will agree, not the most Audio"fool" cable you can get, but sufficiently foolish enough for a cable that won't make a blind bit of difference, right?

Wrong.

Scoff away....

Originally I got it to try between my mains regenerator and amplifier, but changing to monoblocks made this impractical, so it moved to wall to regenerator. How could this positioning make a difference when I am still using basic leads elsewhere?
I have no idea, but I tried it. I left it in my system for a week, just listening to music. The system sounded fine. I didn't notice an immediate difference. Then I changed it back t the standard lead.
It sounded like my stylus had picked up a load of dust. The soundstage and dynamics had flattened. I checked the stylus and it was clean. I listened to a few tracks, and swapped it back to the "foolish" lead. Ah, that's better I thought.
This was not expectation bias, as these things don't make a difference, right?

Still not believing 100% there could be a difference, I subjected a friend to a test without telling him what I was doing and asked which he preferred. His response was "foolish". He preferred the system with the upgraded lead in place.

So what are the downsides?
For me the additional cost reading forums is going to have.
The AG1500 also has the connectors close together and the Furutech IEC connector does not leave much room for the female IEC plug to be fitted in the IEC socket next to the schuko socket.
So after all of that, I have heard the difference interconnect cables can make, and now I have experienced the difference a mains cable has made.

I think I need to go and sit down and try and find the marbles I have lost....

Seriously though, if you have any doubts try it for yourself with an open mind (and clean ears!). They can make a dramatic difference (in my experience).