Remember, RG6 has 0% signal loss over 100 feet. So, naturally 3, 6, 12 or 25 feet will be just fine. These are the prices and lengths for the pre-terminated RG6 cables at "HomeDepot.com":
100' RG6 (Black or White) $15.99
50' RG6 (Black or White) $12.99
25' RG6 (Black or Black) $5.99
15' RG6 (Black or White) $4.99
6' RG6 (Black or White) $2.99
The featured ADAPTOR (4130) can be purchased at "MonoPrice.com" for about 50 cents.
Click here to buy it from MonoPrice right now

Cat5e is a little thin, so use 2 runs to each speaker (one for positive and one for negative)...Keep the pairs twisted just like the picture...But don't twist the bare copper you place into the terminals on your speakers and amplifiers...Just lay them all side by side for a better connection.