Twin lead or coax for downlead from FM antenna?

Use the RG-6... If the antenna in the attic, it doesn't need surge protection; If it is outdoors, surge protection is a really good idea. The issue one should watch is the possibility of added EMI / RFI that can occur when adding a tuner to a system. One time I was troubleshooting this and found when I started disconnecting everything in the house that the downfeed on my FM antenna was picking up some kind of RFI from some local high power CB transmissions. Pounding a copper rod into the ground with a 00 cable attached to the rod and ground bus bar added to my audio ground knocked it out. Everything in my audio system is chassis grounded to this buss in a "star" configuration (which the shield of all my coaxes are also attached to.

I agree that you should run a quad shield RG-6 coax line. I just though I would mention that directly connecting an antenna or cable connection to your audio/video system could have disastrous results without some kind of surge suppression to protect the components. You may also create a ground loop that will cause an annoying hum. I recommend the Monster Power series from Monster Cable. The HTS1000 or HTS2000 will provide protection for all your equipment. http://www.monstercable.com/product_info/infosheet_mpwr_hts2000.html

OK, thanks guys. Since the cable is in my attic which is quite dry, weatherproofing should not be an issue. Now I just have to get my butt up thru the scuttle and switch over to the coax (RG-6).

Coax run should shield noise and give you a better overall signal.

Swampwalker,
I suggest using the best 75 ohm cable you're willing to afford for the down lead. At the antenna, use a 300-75 ohm balun that has a "weather-proof" boot on it. You may want to also use a sealant to keep the moisture out. This will give you a very long-lived, quality lead without picking up other noise. I would recommend a quad shielded RG6 cable. Any Radio Shack will have it. Best Regards, Aaron