question on pwr cords

Once you go beyond 1.5 m from the wall, you must use 10AWG or larger conductors to maintain good energy transfer -- especially for a power amp.

Unfortunately, that rules out anything 'unobtrusive', except for the Aural Thrills "Silver Big One", or the "Triple 10" which are both 10AWG and only about 3/8" in diameter.

http://www.auralthrillsaudio.com/SBO.htm

I have three of them on my Martin Logan electrostats and Depth subwoofer. Great product beautifully crafted. You can speak with Tom Kenny if you need special lengths. Note: although they are VERY unobtrusive (small) they are kind of stiff, so straight runs and gentle curves are necessary.
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"Once you go beyond 1.5m...."

Nsgarch, Can you explain why that is so? Are there any studies supporting this or is is it an anecdotal thing?

What would the aural differences be between (lets for the sake of discussion say) 4 meter lengths of 14 gauge, 12 gauge and 10 gauge cable?

You don't give an indication as to how long you are looking at, but, remember, you could run into safety issues if the powercord is too long.

Best keep them short and go for longer speaker cables or interconnects.

usually best results are achieved if the cables are long enough to reach teh socket... please! you are never going to here the difference between a 1.5m cable and a 2m cable of the same type. stop worrying and listen to the effing music!