Well, I think there are different types, this is just a very normal type of two runs of stranded (quite small in diameter) side by side, like lamp wire, but smaller gauge.
I think the 1mm solid core was attenuating high frequencies a bit, and this could explain some of the difference.
The sound is just more alive in comparison, maybe more finer detail (micro).
This is like this Bell wire on jaycar's site
http://www.jaycar.com.au/productView.asp?ID=WB1700&keywords=alarm+wire&form=KEYWORD I bought it from an electronics supply place, and they called it alarm wire, but there is a type like cat cable.
So with each pair I twisted the stripped ends together to get the needed diameter.