What speaker cable should I use for in-ceiling speakers?
In most cases, 16 gauge 2 core speaker cable is suitable for your install as long as none of your cable runs will be more than 35 metres. If you are running longer than 35 metres, you will need to upgrade to 14 gauge or 12 gauge cable which are both thicker cables.
Using a more expensive cable will not necessarily improve the sound quality. You will mainly need to consider how far you are running the cable, so as to prevent signal degradation.
For outdoor speakers, you will need something weather rated the cabe we would recommend would be the TruSound Weatherproof speaker cable 16/2 UV PE 2-core - which is UV and weather resistant.